Is that paint or a decal, if its a decal, go to local auto body supply store and buy an eraser wheel that goes on the end of a drill. This little marvel will erase tape stripe, leaving the gel untouched.
A buddy of mine has a 1989 340DB and his arch looked the same as yours. Instead paint repainting it he had a local sign shop cut vinyl sheets and put them over the painted surface It looks pretty good. And it was alot easier and cost effective