Kyle, remember the calipers you sold me a while back? Do you recall if they were designed for 30mm or 26mm rotors? I had many sets of 300ZX and Skyline brake hardware in my garage at one time, it's hard to keep tabs on all of them.
The heft of the Z32 brake upgrade is not as bad as you think. It's only the rotors that are heavier. The Z32 aliminum caliper is not heavier than the stock iron 1-pot caliper.
The main problem is the unique offset requirements because of the fat caliper. That's the reason why this brake upgrade is not for everyone.
One last thing, 300ZX brakes require at least a 15 inch wheel.