s14 to a 15 conversion is like those old tercel toyota with a bmw conversion.zenki to kouki is as far as I go.I have the s15 brake convertion but I herd you can go with the 300zx brakes and use the j30 rear end or a 300zx N/A rear end or just change the hubs.its up to you.Still you will need to upgrade the master cylinder if you go for the 300zx that are the same as mines.I didnt upgrade the master cylinder to the 300zx or q45 since now it acts like ABS and you dont want those big brakes locking up.