The real rough and beat up high hour 2040's seem to be (asking) around $6k at the auction houses. The paint issue doesn't appear to me to be the typical throw paint over the rust and dirt to get it sold thing. Other than the non OEM stripes and lettering, it appears to be a reasonable (full) paint job. Why the seller is saying it's not completely repainted is beyond me.
All that said, I think it's worth more than $5k with no obvious problems like excessive blowby, leaks, clutch, good rubber, etc. Maybe $8k, but that is just a guess. It really comes down to how much risk the buyer is willing to take on a high hour tractor.