Ok, time to tackle the booster.
****EDIT 6/6/13****
In an effort to keep things together, and since the rest of the thread (as they tend to do) has taken a bit of a turn away from discussion on specific installation of this kit, I?m making the edit here so that future readers won?t have to trawl through three or more pages of loosely-related banter 
The update is that the 7-inch booster is too small in my opinion, and that opinion is generally shared ?out there? on the inter-webs for a vehicle as heavy as the 63 T-Bird. There are other things you could do but the easiest might be to install a 9? booster ? and that?s what I?ve done. A 9? booster will be about the same as a dual-diaphragm 7? in terms of power assist, but the dual diaphragm boosters are physically longer and when using the master cylinder as in this kit, along with the original booster bracket, you just won?t have room. The 9? fits perfectly though and the only modification was that I had to shorten the threaded rod in the back of the 9? booster so that the length of the threaded rod was the same as that of the 7? ? so hacksaw, cut-off wheel, etc ? nothing crazy. The 9? booster I used was an aftermarket booster ? same or similar brand as the 7? ? very common to find them in hotrod magazines or the web- ebay as well if you?re into ebay. I bought mine from ebay as ?slightly used?. Since I wasn?t sure it would fit I didn?t want to buy a new one, ? but it does fit and as an added bonus, also works just fine. I need to adjust the booster to M/C pushrod to account for some pedal travel, but regardless of any adjustments I still need to make, you?ll be happier with the 9? booster and I?d recommend it over the 7?. Note that the modifications and installation as below all apply to a 9", only thing that changes is the size of the booster 
The good news is that if you have a 65 mustang, chances are this booster (7") will fit!....whats that? this is a Thunderbird forum?........
Somebody should have had that conversation with Auto City Classic....( actually somebody did...me.....I sent a very nice email, to which they have yet to reply....) but I digress....lets get down to it....
The first thing I need to do is ask for forgiveness - by the time I figured out what needed to be done - (which ended up being simple, but I was tired and hungry and annoyed, so it took longer) I had forgotten to take pictures
So instead, I searched the vast inter-web for appropriate pictures that would let me illustrate the steps, and then stole them
OK - this is actually the exact booster that comes with the kit - picture comes from the kit itself, I just didn't take it.
So whats wrong with it...well....
1) Either the bracket is on upside down, or, the bracket is designed for a different make of car. In the picture, the "pivot point - (item 1) is at the top, it should be at the bottom. I've rarely seen a booster mounted as shown in the picture - for one thing, the angle of the bracket tends to push the booster further down into the engine bay rather than lift it up, which is also more typical. Either way, point is, the only way to mount the booster in this configuration was to turn it upside down....not that it mattered...see item 2:
2) Regardless of how (or if) you mounted the booster, the rod was several inches too short. A quick comparison to the stock rod made that clear.....but again, rather a moot point, see item 3:
3) The bolt holes did not line up to the fire wall holes - period. I don't care if it was upside down and too short, it wasn't getting bolted in anyway. An added frustration was that the original bracket had pressed-in bolts so that you could A) get the nuts on the other side fairly easily and B) not drop (and consequently, loose) bolts out of the holes every time you nudge the booster.
So long story short - clearly this was an assumption made by Auto City Classic...."
if it fits other fords, it will work for the T-Bird"
The solution was actually very simple, but since I wasn't aware of all the "upside-down, too short, wont mount anyway" issues, I had to work my way through them to get to it. so..whats the solution?.....quite simply, mount the new booster to the old bracket.
First, remove the bracket from the new booster, including all the linkage, you'll be changing that too. You'll end up with this:
Next, lets look at the old bracket and linkage...
1) You want to attach the booster push-rod to this linkage. Item 3 here indicates that you may need to run a spacer or two on each side - I used washers - all they need do is take up some of the space and center the push rod.
2) Here is where you need to do a bit of modification. The old booster's mounting studs are a little further apart top to bottom, so the holes in the bracket will not line up with the new booster's studs. The good news is that its close - you probably only have to elongate the bottom holes a 1/4 inch - the yellow highlight marks the spots. I used a Dremel tool with a grinder bit. Best thing to do is put the bracket on the top booster mounting studs and then see how much you need to enlarge the bottom holes. You can of course do the reverse, modify the upper holes.
The fit is tight because the center bore of the new booster seems a bit larger than the old one, but it does fit. In an unfortunate bit of strategy on my part, I had previously removed one of the pressed in studs on the old bracket by unceremoniously whacking it with a hammer. This did two things - removed the bolt and bent the mounting plate a bit. As a result, my bracket didn't quite line up with the firewall holes anymore, and I had to bend it back into shape - my point in telling you this is that while I don't
think you'll need to do the same, I can't be sure the width of the new booster mounting studs wasn't slightly narrow versus the old, so you may also need a minor tweak to get your bolts to line up - but very minor.
Ultimately, you'll get something like this:
NOTE: This picture does not show the correct mounting bracket (stock '63 at this point in the build) but it is close enough for me to point out the important parts.
1) be sure you have installed the bracket with the pivot point down.
2) Make sure you have added the necessary spacers and used either the cotter pin or retaining clip so that the booster push-rod stays put.
3) Don't forget the spacers! There are 4 spacers that go between the booster and mounting bracket - they are thicker than those shown here, but same function and location.
4) Number four has nothing to do with the booster, but its a good time to tell you about another modification. The "proper" mounting location for the proportioning valve using the bracket provided in the kit, is on the stud that mounts the master cylinder to the booster (as shown with transparent prop valve). However, there is no room to do this because the shock tower is in the way. The simple solution is to locate the prop valve a few inches further back and then use the bottom booster-to-bracket mounting stud instead. You wont be able to use the provided Prop valve to Master Cylinder metal lines, but you've no choice really and making new lines that fit is easy enough.
Lastly - I felt some of the linkage lacked the free-play of the old booster - again it could be that the bracket was narrower than before. Everything worked, but seemed tighter - so I applied some good lubricant to the moving parts - pivot point and push-rod link mostly.
I installed the booster and hooked up the brake pedal -everything seems to work and function well with no hangups or issues - works very smoothly.
Here is a shot of it installed in my car:
Well - that's the booster. Next I think I'll cover the proportioning valve and brake lines, so, look for that soon.
but the next day I just naturally thought "why not cut it off you idiot" and the hack saw worked wonderfully - almost as though its made to cut metal...... 
It took mere minutes and I got this:
