Reuse any 7-1/4 parts on 8-3/4?

If you are keeping the same brake bolt pattern then the brake parts. I don't know if the yoke straps and the bolts are different or not. The yoke itself is different.

I had a 58,000 mile 7 1/4 BBP that was complete drum to drum and no one would even come get it for free. If you get lucky enough to find someone that needs it you might get something out of it.