In general, the mid to late 70's 11.75" setup is best bang for the buck. Plus replacement parts are readily available. There are lots of ways to do this and the attached "disk o tech" from MA provides a good starting point. It requires 15" minimum wheels. Master Power Brakes has smaller rotor kits that may work with 14" wheels. I understand Dr Diff is and expert in all this area.

http://www.moparaction.com/tech/archive.html