You'd need the S14 -> Z32 brake lines....but yes you can leave the rear stock if you want to and it'll be fine. You could save some money and get a Auto S14 MC/Booster, Q45 front brakes, nice pads, and use your stock lines (since Q45s bolt to stock lines).

OR you could buy nice pads, rotors, and SS lines all around, get an Auto S14 MC/Booster and call it a day and have a pretty decent brake upgrade that way.

Are you boosted/making a lot of power/road racing/using your car like that at all?