Don Epps used a t5 and it looks like it fits well and you don't have to relocate the pedals. First thing- have you checked your bolt pattern on bellhousing. A pre 48 bellhousing won't do but a later one will have a pattern which allows you to bolt in almost any trans you want. I used a New Process 89mm 4 spd od and it fits well but is side linkage and I had to relocate pedals. If your b/h is old pattern, you could take the Jim Proffit approach and use adapter plate and **** T-OD trans. Rick's rear end idea works, but decide if you will stay six lug, otherwise upgrade to a more modern Camaro r/end. Axles and brake parts can be an issue if you go Rick's route-- but it is the most authentic looking.