I would walk away. If it's in as many pieces as you say he'll be chasing you down the driveway to take the pile of parts and clean his shed. Heck he probably doesnt remember how it goes back together either. Remember that every seller thinks just because it's old, it's rare. Its not.
I paid around that for mine and it was complete, almost running (head gasket, some other comparatively minor stuff).
A couple of months from now he'll call you and offer it all for $200 if you still want it.
Does it have a good title? What are your plans for it? Stock? Modified? Full custom street rod?
Any idea how many parts are missing? Or where you're going to find them? Or how much those incidentals are going to cost?
Other members may have a different opinion than I do so be sure to get as many opposing opinions as you can and weigh them objectively.
Good luck with your new truck or your continued search, whichever it may be.
