Jeez man, you are doing this build properly. It's good be a beast when it's done.
Were those 4-pots stock on your car, or are they nicked from a 300ZX? I remember people talking about how good they were back in my old Subaru days; apparently they bolted up as well as the Subaru 4-pot/2-pots.
300zx 30mm calipers. A little trick I learned working at Autozone, no one there knows the difference between calipers so you can use your single piston junk as cores for the 4 piston big brakes. It cost me less with the terrible employee discount to get reman calipers than used, just pay the core charge up front and come back with the worthless cores later.
The car will be going lower now that it's mocked up. Thinking about getting a new set of coilovers, mine are almost 8 years old that I initially bought used for cheap being broke at the time. I also have a fender roller for the rear once it warms up a bit.