8.75 Rear End Drum Brakes

Ok guys....here's what I have. I did not do the work, so I am trying to figure this out. Believe it was an early Barracuda that donated it's 8.75 rear for my 1975 Duster. Rear end has upgraded axles to go to the BBP. When I pulled the rear wheels off, I found a wheel spacer between the axle and the brake drum. I asked the guy who I bought the car from and he said the shop he took it to put them on that way because the drums were rubbing on something. I believe that they got the BBP drums, but did not change the backing plates for the brakes. Does this sound right to you guys? I know that if I remove the spacers, the drums hit so hard they almost lock the axles up. I was thinking it was only the drums since there are two different ones but the backing plate could be the real culprit. Is there a way to tell? I am really thinking that I should just convert the rear to Disc's and eliminate this headache.