I have a 73 Challenger with a 440, very well done and it took great effort to get it insured for $30k. Using that as my reference, I'd say that it's overpriced for the car as it sits. But you can look at it another way. If you found a rough 74 for let's say $5000, would it cost you $20K to get it in the condition you see now? I've spent that much so far on mine and it was pretty decent to begin with. All those little pieces can really add up. It's sucks spending $1500 at Year One and they send you everything you've bought in one medium sized box.
If you're not a body man or just don't want to spend countless hours restoring it, then it may be worth it to you as the sum of it's parts, but not the whole. If you want it, offer $20k and see if he bites.