I don't understand why anyone would keep SBP. But the SBP Pirate Jack, DoctorDiff and Wilwoods kits may not work with most (if not all) of the factory SBP wheels.
I also recalled another reason why there would be two different hub bore diameters for the SBP wheels. The 73+ 10" drum brakes were SBP, but had larger wheel bearings. So they would have needed a larger hub than the earlier SBP drums had.
Sure, but are your SBP 14x5.5" Rallye wheels factory? The aftermarket reproductions also have different diameter hub bores.
Since you have the Pirate Jack kit, what is the actual hub diameter on the modified '73+ rotors? Posting that would make it easy for people to check their own wheels and know for sure.
