As pathetic as it sounds, I have spent hours pouring over different MC's on Ford and GM product using the Rock Auto site. You can look at the shapes of the unit and get all their specs like piston size and port sizes. GM liked to use bigger MC bores as a rule. A bigger bore requires more pedal effort OR more booster (uh oh, I feel an uncontrollable ramble coming on..)
Some GM MC's are really wide where others are narrow like Fords. I suspect the wide body units would have clearance issues for us but the narrow ones might just work out. I need to double check but I seem to remember that both Ford and GM MC's use a 1" stroke.
I think some of the 70's mid size GM cars could be a very good fit for our application.
Here's a good example: https://www.rockauto.com/en/moreinfo.ph ... 94&jsn=470
This MC has 1.125" (1 1/8") Piston where our 65/66 was 1". Becasue that's what Ford used on 65/66/67 Tbirds, I used a 69 Mustang MC with that same 1" bore but now after driving it a while, I feel that a 1.125 would work better. If I changed nothing else, it would require slightly more peddle effort for the same stopping power but could apply more power overall to the discs. All hypothetical though, I don't think the GM MC will just bolt up without some grinding and I couldn't find a Ford MC that's 1.125".
Now the question is, What size booster to use with the above 1.125" bore MC?
A 9" would *work* but a double 9" or a 10" would be better if
we have room. A 12" might
work great but you can have too much boost too. Then the brakes become grabby.
GM used 12" boosters quite a bit for large cars and trucks but combined them with MC's that had even bigger bores (the wide body MC's?). On the other hand, our cars aren't exactly compacts so this combo might work fine (but there's little chance we have space for a booster or MC that big). Of course, there's always the hydroboost route that gets rid of the booster altogether...
Then there's an off the shelf booster/MC setup a lot of the tri-5 guys are using. Something like a dual 7", 8" or 9"?
Oops, there's that fitment issue again..
Oh my, that was a ramble.
1964 Coupe Wimbledon white/Rangoon Red w/black int. Owned for 42 years. It was my folks car before that (second owners). VTCI # 12013.