Here's what I did.... Just did it actually: 12 bolt from '73 truck
Bought this kit:
http://www.getdiscbrakes.com/trd4705
drilled axle flanges to 5x4.75, drilled rotors to 5x4.75 for 7/16" studs.
The caliper brackets from this kit... only 2 holes line up unfortunately, so it is mediocre quality.