'55 Firewall - cables and wires

[wex65]

The day when I will need to start feeding the myriad of cables and wires through the firewall is fast approaching; tach, choke, speedo, hood release etc. I am also somewhat scratching my head trying to work out which wires go through which hole. Does anyone have a layout in terms of what feeds through where? For example, the large grommet, pictured below, which has four holes...

I am guessing 1 is for the main loom. Can anyone enlighten me as to the purpose of 2, 3 and 4? The odd shape of 3 maybe hints at a specific role.