need rear end help(72 demon)

i put new Yukon axles in my 8 3/4 and newer style drums (o'riellys) from 73 and up large bolt pattern. everything seemed to go together ok, but when i put the wheels on and tightened them up it locks everything up. long story short...the inside lip of the drums hit on the inside of the backing plate. so whats my best option to fix this? thanks in advance