1989 Chevy Caprice rear drum brakes

I already bought the new backing plate with the bolt on wheel cylinder and it is completely ripping the two bolts out of the back of the wheel cylinder as well as the mounting pin that holds the brake shoes in place that is located right above the wheel cylinder. It completely distorts the backing plate and oblongs the holes every time I put it back together. I welded the wheel cylinder in place as well as the pin above it and has yet to brake but it only a matter of time because something is putting a lot of pressure on the shoes. The only thing I have yet to replace is the drum. The whole emergency adjuster and arm and components and springs and shoes are all new. Wheel cylinder pin and backing plate as well. I also just mounted and balanced two new rear tires. I noticed at the junkyard when I was getting a stock backing plate that the drum had a quarter sized led weight or spacer about a 1/4 inch thick between the outside of the drum and between the rim. Is that an old fashion way to balance the drum or is that needed to cushion the pressure the wheel puts on the drum