3rd Gen Transmission swap

I have a 1987 Firebird. It used to have the 2.8L Multi-port injection, but then it crapped out on me. I then took it under my wing as a project and dropped a chevy 350 in it. i bored it out 60 over and had a '70 Muncie M-20 wide ratio sitting around in my uncles garage. I started putting it in and did so until i have just now ran into a problem. i can't figure out how to hook up the stock linkage to the trans. i know i had to make some mods in order for it to work correctly, but its over my head now. does anyone know of a replacement trans such as the T-56 or so on? if so...does anyone know where i could get one? i dont think the T-5 can handle the amount of power i'm putting into this thing, anywhere from 375 to 400 hp.

no the T-5 will not...A muncie 4 speed would be nice...My friends got one in his 84 camaro. Well, you could also just get 700r4 rebuilt and put that in.

i would go with 700r4 there not the best racing transmission it isnt bad but its ok it is heavy duty or you could go with 5 speed that comes stock in trans am or camaro