How much rust is too much?

Well guys, thank you for sharing your thoughts, it's exactly what I wanted to see. I was leaning toward parting it out and building another car.

I'm not ending the poll, but the solution has abruptly presented itself. I won a much more solid A-body from ePay, so the 1975 Duster will be sold complete to a new loving owner.

Meanwhile I have to start looking under seats and beds for spare change to pay for the new car, arrange shipping etc etc.