Hi Boys,
In my opinion, that body isn't that bad overall. Yes, the PO didn't finish off the filler very well, but it looks like the sheet metal was sanded and then covered with spray can primer. The rust on the rear fender is typical of metal sanded down to bare metal and given a couple coats of primer and then left in the weather. without sealing it will always rust in a few months.
Anywhere the original paint is still in place, don't take it off, use it as a base.
I would wet sand the whole thing with 220 or 330 grit. I would expect you would find 80% of the body ready for nothing more then another coat of primer. Even that rear fender will clean right up with wet sanding.
5 gal bucket of warm water with a little bit of something like Spic & Span or simple green and keep the area wet and rinsed with the hose.
Then evaluate where the bad spots are.
Note the areas you sand have to be dried and covered with primer within a day to prevent surface rust.
