72 340 Demon too far gone?

A few years ago I parted a 71 340 4 speed Demon. It had a lot of rust, but compared to what yours sounds like and also the one pictured above, it was a restorable car. It osunds like either could be restored but would require much more work than most other cars. I'd say stick to the advice you have already received and restore the one you would rather have when done or use both for parts and get another car going.