The pedals are suspended and the key part is a clutch cable housing that will take the cable through the firewall and allow it to be adjusted. This was found, very handily, on a 1980's Citroen 2CV firewall....
I cut it out using a cold chisel, tidied it up and if fits perfectly - the curve at the bottom matches the "shelf" on the Model T firewall and locates it exactly where it needs to be.

A 2CV clutch cable looks the right length but I've get a box of GM clutch cables of various different types so that I can mix and match. Pedal end is sorted and works fine together, the pedal ratio is 7 to 1 with 1.5" of pull on the cable - so about perfect.
Next stage is to make a bracket to go on the gearbox for the other end of the cable. May use a bellcrank to get a better cable line.
There's an excellent thread by DRuss32 that gives some ideas on bracketry...
