8 3/4 backing plates onto a small bolt with upgraded big bolt shafts

Ok thanks for the quick replies. So if the axle shafts I get are ,"a body flange offset". Another thought popped into my head, is it possible to find 10 inch drums in the big bolt pattern?

Just a thought as to where my head was at before I started this thread.
I was thinking that if I started with a factory a body 8 3/4 rear end (obviously the small bolt pattern) and all I did was swap the axle shafts to a shaft that has the big bolt pattern nothing changes. But then I remembered from somewhere in the dark recess of my brain, I vaguely remember something about needing new backing plates. Maybe because I wouldn't be able to find 10 inch drums in a small bolt pattern.

PS
Just to clear things up as I am not sure if all a bodies that came with the 8 3/4 had 10 x 1.75 brakes like mine does.

Yes, you can determine just from the backing plate if your 11” backing plate is for a 2”, 2.5”, or 3” drum. The offset on those plates is different, and can be measured using the process I describe in this thread
Converting rear drum brakes from SBP to BBP

The measurements for the plates are there too