Ive just seen this thead and i just wanted to tell you that the z32 calipers wont work on the B13 hub! Ive got a set of calipers and pulled the hub off my car to get a good look, because i was going to make a bracket. there just isnt enough room. You are better off just getting the B15 hubs and haveing them redrilled.
BTW im a journeyman machinest, or i wouldnt have tried to make the bracket. I will try to get some pics in the next day or so to show everyone.