Rear drums rubbing

Hello I have a small bolt pattern dart with a 8.75 rearend. I switched it to large bolt pattern Moser axles. I bought 10x 2 1/2 backing plates and shoes. They bolted up fine. I purchased Durago #8878 10 inch drums. I put them on and I have alot of rubbing going on. Wear marker of rubbing on the back plate and the brake shoes.
What's my issue.....please help I'm so lost at this point