'93 E350 Motorhome - really frustrating brake problem

I have a old Indian motorcycle and remember that after the drums were machined out on a lathe, the new shoes were shaped on a machine that sanded the shoes to match the arc of the drums. If this was not done, the new shoes would not contact the drum evenly and brakes would be ineffective until they wore into the same arc as the drum. If the shoes do not match the drums, adjusting may make the brakes drag but they won't be effective. (At least this is as I remember drum brake technology.