Don’t take this the wrong way.
For $6000 I would expect a 50 year old car to have some underbody issues.
If one area of the frame has heavy rust, I would expect to find heavy in other areas.
That being said, if you got a complete second generation Barracuda, that needs some under body repair for the price mentioned, your deal was not a complete disaster. Like you said, it is the car you wanted, the exterior paint is good enough.
If I had paid $12000 for the car, I would have expected better. Look around a see what you get for $6000 on late model cars these days, not much.
