I'm not sure on the hub fitting, if it's swapped to 5 lug using known working parts then go for it.
The rotor will slip on no problem, you might have to have a bracket made to align the caliper properly over the rotor though.
As cheap as Evo Brembos are getting, why not pick up a set of those - a guy on Zilvia sells the adapter brackets as well. The stock evo brake line does bolt up to our hardline on the body.
Well u don't need the hubs. Im rocking 350z track rotors 13inch with 300zx calipers. Just needed an adapter bracket for the caliper to work with the large rotor.
U can also do the 350z caliper with 350z rotor it bolts on just need a spacer. Nico club and zilvia have write ups on this stuff. Google search next time its been cover before. Also I hope ur talking about the 350z brembo brakes!!!
Well there are lots of options for brake upgrades without spening insane of mone for the off the shelf performance brake kits
J30 brakes
Q45 brakes
300zx brakes
300zx calipers with 350z track rotors
350z track brembo brakes
Vr4 3000 gt/dodge stealth brakes
Mustang cobra rotors with 300zx calipers
Mitsu evo brakes
And more.... just search there all better then shitty stock brakes. And depends on the performance ur looking for and money u got!!!
But remeber u gonna need to upgrade to a larger brake naster cylinder when going to multi piston calipers. The stock one just won't cut it. Recomend the z32 brake master cylinder 17/16 size. For even better braking get an automatic brake booster. With that combo u can't go wrong.