Unfortunately, the dipping and e-coat providers are pretty limited due to the EPA constraints. There used to be a ReadiStrip in PA, but I believe it's closed up. The only place I know of that will strip and e-coat in the same facility is International Paint Stripping in Michigan.
Niles Mfg is in Ohio but they only do coating:
American Metal Cleaning in Toledo can prep the body for e-coat:
AMERICAN METAL CLEANING, INC.