73 Dart 4 door leaf spring bushing size?

Springs are fine, I just need a little more lift in the back end because I use the car as a “mobile mechanic” having 700 pounds of tools in the trunk she tends to hit the bump stops pretty often
If your carrying around 700lbs of tools and riding on the bump stops, the springs are not 'fine' for what your doing with the car. buy a decent set of springs with enough rate to handle the extra load.