the dash has been painted, the vin tag should have a white Chrysler Corporation decal on it.
I've seen worse on the trunk pan. To be as nice as the rest of the car does, it should be replaced, but you could clean and paint it and worry about it another day.
not sure what you mean by centre column....steering column? a 40 year old car won't have the same tight feel as a new car. plain and simple. You get used to it, as long as it isn't excessive.
The vin numbers on the trunk rail are under the trunk weatherstrip, which if it's glued down as it should be, you couldn't see them.
the master cylinder is unpainted when new, so surface rust is normal. What else was rusty?
brakes...rears just my need adjusted, and the front sounds like a caliper piston hanging up. I had one do that so bad I could make a sharp left turn without turning the steering wheel.
what was the price on the car?
If your gut is telling you to keep looking...then listen to it. Keep looking and saving your money, and get the nicest car you can. and not a bad idea to look the GTX over just to compare things.
