The 510 Realm

I'm not aware of anyone having answered any of your questions. Most people going this route want the bigger rotors and want to ditch the heavy ZX calipers. Are you looking at wheel fitment issues? Wheel spacers aren't an option?

Julian, no real issues at this point. I have multiple sets of the 280ZX stuff around, and also potentially looking at keeping the ability to run 13" wheels for track time or autocross along with 15" for the street.

Do you mean wheel spacers instead of the 300ZX hubs? I actually have some which could be used. I have not tried the combos on the car yet. My car has flares, and will utilize coilovers eventually, so want to fill the wheel wells as well as fit the struts properly with 7" wheels.

Did some measuring on the parts, and inserting a spacer between the rotor and hub looks like it could work. I will have to mock something up to check caliper fit.

The main sticking point in using 13" wheels with the ZX front brakes has been caliper/wheel clearance. The only 13x7" wheel I remember fitting is the Libre, and that required clearancing of the inside of the wheel at the spokes. Not a lot, but still.

So with either the Z31 hubs +.75" per side, or spacers, you'd be pushing the wheel out and creating clearance at that point. Pretty sure spacing the Libre out that much will cause you to run front flares, though.