I realize this is the 2nd generation forum, but thought you folks might have some familiarity.
My wife fell in love with an original (except paint) 142s. The car looks to be a good driver with some rust (previously repaired, I think, popping out in the end of the rockers. Minimal bondo found and inner rockers seems very solid as are the floors and jack points.
My question is in regard to the rear wheel wells. On both sides there is rust through behind the tires into the trunk area. Just sheet metal The driver's side is a bit more serious than the passenger side as the rust is on the sheet metal down to the "frame rail" where the shock attaches. Frame rail appears to be very solid and no sags, etc. Can I repair the wheel well sheet metal if the frame rail and support area is OK or does the rail need to be cut out for the repair?
Left is toward front.

 

Hard to say with one picture. It all depends on your skill level and how much rust is there.

 

whatever you see, there's sure to be a lot more hiding where its not so obvious.

this is a nearly 50 year old car, that probably hasn't been garaged its whole life.

the 'correct' way to deal with that sort of thing is to completely strip the car down to its chassis, sandblast everything down to shiny metal, solder and/or braze new sheet metal wherever its rusted through, then repaint, and completely rebuild/restore the car. a vintage Porsche or rare model Mercedes might be worth that treatment, but a Volvo 140? hardly. You'd be looking at a year+ process, and a lot of room to end up with an ugly car if your bodywork skills aren't up to par.

 

sure you can repair with sheet metal but as Pierce was suggesting, you need to determine if its rusted on a structural component and the true extend of the damaged area. If you have welding skills and some fabricating tools you can probably close the hole up but it may be worth paying a restoration shop to inspect for problem areas, particularly where a non-professional repair was done previously (ie, what's under that bondo?).