Cass is definitely the guy to talk to! :thumbup:
BUT, 7 1/4 backing plates WILL work if they're from a 5x4.5" pattern 7 1/4. In fact, any 5 x4.5" pattern 10" or 11" rear brakes will work with BBP axles, the axle offset is the same for all of them. Any 5x4.5" bolt pattern 10x2.5", 11x2", 11x2.5" or 11x3" brakes will work with BBP axles. They can be from a 7 1/4, 8 1/4, 8 3/4, Dana 60 or 9 1/4" rear end as long as they've got BBP axles.
The only other wildcard is using the 11" brakes, the backing plates have to be matched with the drums and shoes because the backing plate offset is different so that they all work with the same axles. Ie, you can't put 11x2.5" shoes and drums on 11x2" backing plates.
