Info on 7.25 to 8.75 backing plate swap

Yeah, 10.5" rear brakes?

Anyway, those will probably work. Are the brakes from your 7.25 9" or 10"? If 9", I'm not sure how easily you'll find all of the hardware, especially the e-brake stuff. The e-brake cables themselves should work. I had to reuse them myself when I swapped from a 7.25 to an 8.75 and 11" brakes. If it were me, I'd prefer to find an 8.75 setup, complete with drums. Then hopefully you'll have everything you need that you can't easily find at the parts store.