Question after converting a 7-1/4 to 8-3/4

I have a question. I have a 73 Duster with a 7-1/4 in it currently, and I have an 8-3/4 I'm going to put in it over the winter. The bolt pattern for the 7-1/4 is 5 x 4.5 (LBP) and the brakes are 10 x 2.5 too. Can I change out the current brakes & hardware to the new rearend using the same backing plates? I just replaced everything last year on the 7-1/4. Second question is will I gain any width and extra back spacing when I swap out the 7-1/4 for the 8-3/4? Thanks "StrokerScamp" for suggesting starting my own thread....
"19"