Let's not let this thread end here! Too much yet to clear up.
What other "bolt on" brake upgrades are there for rear? How well do they stop compared to each other and which have handbrake issues.
Also, which brake combinations do and do not require a proportioning valve?
From what I have understood so far, the list for rear starts with stock drums, 280ZX disk, R31 disk, R32, 300ZX, AZ Car Wilwoods.
Surley R31 disks would be a HUGE improvement over stock drums. I doubt whether you would feel the need to upgrade again Mick.