standard s14 brakes wont be bigger than 300ZX brakes unless the 300ZX hes refering to are the 26mm not the 30mm (theres a good show of images in that link i posted so you can know exactly what your getting.) In which case if they're bigger than the 300ZX or the R32 GTST brakes (the ones im running) you'll have one hell of a time finding wheels to clear them in terms of the spokes making contact with the caliper.
In terms of wheel diameter you'll probably need at least 17" to be safe. But offset wise you'll have to pay for a decent set of rims to clear the spokes, unless you run spacers.