Here's the thing. People always say you HAVE to take it down to bare metal. 99% of the old Mopars out running today, and that are not still sitting in the pasture, have been repainted at some prior time. Therefore they will have some amount of filler (Bondo). So you take it to bare metal, grind away the filler, and guess what, now it requires the filler to get it smooth. MORE $. Or someone's labor pus that good $100 a gal filler. and paper.
If that filer was done the old fashioned way before it was applied over epoxy primer, but over bare metal, there is where the problem can arise. If that bare metal was not perfectly clean, and surface rust has started under that filler. That leads to problems.
I have seen plenty of these old cars with the OEM paint that has a wonderful base for further prier/paint. Good body shop will take it to bare metal and therefore guarantee there $100 minimum per hour work!!
Sometimes, perfection is not in the cards, and a repaint over cleaned scuffed paint is the answer. Easy to figure cost of materials, the labor is where the big question lies!!!!The question is, whats ya car worth anyway!!???