Hi mate, as far as I know MT75 should bolt right up to the pinto engine. You would have a bit of travel on the clutch release bearing cause I believe the dohc engines had a thicker flywheel(Please anyone correct me if am wrong).
check out exhaust collectors on line, it might help you visualize what i mean. its is the merge into which all the 4 pipes (primary pipes) from the engine exhaust mounting face goes into. The exhaust silencer is then connected to this collector. My one is 4-1 though.
I do apologise it it comes across as if am trying to teach you how to suck eggs, just trying to explain it how i see it. lol
Regards
Femi