I recall that at least one 1973+ retro-fit kit is adapted to SBP studs, so pursue that line of questioning. Personally, I wouldn't want the 1973+ setup since it uses a single-piston slider caliper and parts appear heavy. One advantage is the rotor-hub is integral so getting a new rotor gets you a new hub (hubs are hard to source for earlier cars), but downside is when you can't buy rotors anymore you will be stranded on hubs. K-H and Wilwood are fixed 4-pot calipers (like high-end cars today) and work w/ SBP. But, sounds like Scarebird is best for you (ebay).