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

I am doing this swap currently. I spoke with doctor diff the other day and he verified that yes, you can use the backing plates from the 7.25 if they are big bolt pattern axles. I have a '75 Scamp with discs up front and drums in the rear (5x4.5 bp). I will be using the whole brake setup from my 7.25 onto my new 8.75 housing.