Keep us posted on what you work out.
I wanted to go Cruszida's options of nissan 4 spot callipers, but i chucked my rims onto a r33 skyline and found out that the calliper is bloody huge, i don't know if the disc (and thus the calliper) would sit further back however if it was converted onto the ra40 hub and strut to allow for a suitable gap between calliper and rim back. (will be trying my rim on a 300zx this weekend to see if that is any different)
I don't fully understand how it works though.
looking at the dba catalouge
the ra40 disc is 254mm diameter
12.7mm thick rotor
16mm height from face to back of rotor
the AU disc has a much larger distance between the face and the back of the rotor.
AU is 287mm diameter
24mm thick rotor (28 for the AUII)
and 65mm height from face to back of rotor (70mm for AUII)
and in case you were wondering the pugoet 604 rotor had 43mm height but that is using the corona hub so it doesn't quite relate. and the nissan 300zx is 54mm
so i assume it is not just a simple case of bolting the disc onto the ra40 hub
the difference in heights however might have something to do with the rotors going over the hub rather than being bolted from behind however, i don't know, but this would then imply the studs would be too short. i am only beginning the research on this myself.
Norbie has MA6x brakes on his ra28 but he had a bracket made to get it to work, expanding on that theory would give Cruzsida's method for nissan brakes however i think.
Rob RA40 helped me a fair amount for info on the corona/hilux method as well which still seems the easiest and cheapest (no custom parts needed) option.
but i would like to know what research you find...