Help! How much space gained by rolling fender lips on '70 Dart?

Rolling the fenderlip won't help.
Whenever the body moves downward on bumps, the inner fender will contact the tire.
Remove the tire and look up to the inner fender. There's an annoying ridge that will contact the tire.

The proper fix is to move and reweld the center of the wheels for more offset. That is, if you still have room to go inward.