Rear end swap

Working on a 1968 Barracuda
Installing 8 3/4 rear end. Have the housing and 3.91 SG. Has the 5 on 4" bolt pattern. Will the backing plates from a 69 Plymouth Belvedere 8 3/4 with 2x21/2 drums with 41/2" bolt pattern work? I know that I have to cut the axles to fit.
Thanks
Dave