No, you can't just re-drill the axles. The offset of the axle flange is different between the SBP and BBP axles, so the offset on the backing plates is different. If you mix and match between SBP axles and BBP backing plates the drums aren't centered over the shoes. I forget which combo leads to which, but in one case the drums bottom out on the backing plates, and in the other they're about a 1/4" short. The two incorrect combo's would be BBP axles with SBP backing plates or SBP axles with BBP backing plates. Either way it doesn't work. If you re-drill SBP axles, you have to use SBP brakes and re-drill the drums too.
Stock LBP axles don't exist for A-body 8 3/4's. The 8 3/4's were phased out for the A-body when they went to BBP, so the only way to get A-body BBP 8 3/4 axles is to either buy aftermarket, or have a set of truck or C body axles cut down and re-splined. The later BBP A-bodies came with either 7.25" or 8.25" rear axles, and those rear axles are not interchangeable with the 8 3/4.
