Combination calliper/handbrake solutions are not as good as dedicated calliper/disc and independent parking brake solutions. The S14 and S15 both have rear combination brakes. A relatively straightforward conversion is to fit the rear brake setup from the Z32 300ZX.
If you are running more than 12psi of boost, you should really upgrade your fuel pump. The standard fuel pump will start struggling to deliver enough fuel above this and that means your could start running lean at higher revs. Running lean means Det and bye-bye engine. Even if you simply need to replace the fuel pump, replace it with an uprated pump, as it will undoubtably be cheaper than the Nissan replacement.