[Northern 52]

I have little experience with body work and could use some advice for dealing with rust pitting. My cab, hood, and fenders, which are very straight, sat out for many years in an acidic environment. The surface rust has pits that don't sand out and I'm afraid if I keep at it, the metal will be very thin. Is there a prep or a process to take care of the rust in the pits so they don't come back?

Thanks