A bit of a nightmare. I bought the 300SD three hours away. Had it inspected by a mechanic who didn't know either me, the owner, or the car so that he was totally independent. On the basis of the car only needing new tires, a hole in the inner fender being fixed, the front exhaust pipe, and the parking brake fixed or adjusted, I bought the car.
Turns out that hole wasn't in the inner fender but in the frame. There were two other frame holes. It needed new pads and rotors all around and two new calipers. Plus new belts and an alternator adjuster. I haven't received the bill for the frame work from the restoration shop (it was supposed to be under $1,000), the tires were $500, the exhaust work around $600, and the mechanicals around $2,500. Plus the cost of the car itself ($2,900), makes for an expensive car. Plus the incipient rust that will exist in the box sections waiting to pop out (as they did to create those holes in the frame).
The rust was fixed by cutting out, media blasting, then epoxy primed and painted: its properly fixed. The concern is what's going to appear as time goes on. Since the goal is to drive such a car for many, many years, this particular car may not do that for us.