I'm getting a COMPLETE 4th gen disc rear and replacing my drum rear. What all will I need? SOmeone said a new master cylinder, someone else said proportioning valve only? What about the Ebrake cable?

 

Proportioning valve should suffice. Ebrake cables need to be elongated somehow, I am still working on that one

 

Get a valve from a wrecked 3rd gen with factory rear disc. I had to splice my brake cable from the 02 camaro that i got mine from. But i just got it to work. it's worth it..

 

ebrake cable is the toughest one.
I've heard 91 or 92 1st or second design cables work, can't remember with year or design, but it's one of those combos.
Some people have made custom plates to mount the stops for the 4th gen cables to work.

I haven't fixed my ebrake yet, will do it sometime in the future.
Oh, and I've been running a 4th gen rear for almost 2 years.