I threw a set in the trash that came with a car . Same issues. But measure the difference from side to side shim the close side back. Make a shim for the hanger in the front. Moat A-bodies are off like that vary easy to see under the car. The brace that the spring hanger bolts to will be located different from side to side compared to the hole in the frame underneath. After I shimmed mine the car stayed straight heating the tires.
Did you ever see a car going sideways while doing a burnout and someone has to hold the car or it would spin in a circle? This is why. Check you will see what I mean
I mentioned this because you said one side is close