i'm guessing not too much, the rear hubs shud bolt in all gud, you shud get a31/s13 cntrl arms pressed into the front hubs,
the only thing dat i'm not too sure on is if the a31 rear half shafts fit in the hubs
i no theres been at least 1 cefiro wit r33 hubs, but i've seen at least 2 cefiro drivers sell their 5 stud conversion kit from a r33
GL