Sounds like a 77 or 78 engine. Is it a 4 speed, 5 speed, or automatic? Was the car a coupe or a 2+2? The propeller shaft lengths will be different between those two. The extras for the engine are where a lot of value could be. ECU, AFM, alternator, ignition module, distributor, injectors, fuel rail, FPR, throttle body, BCDD, manifolds, EFI relay, etc. See if you can get a list of the extras and their condition. If the seller has been selling off parts piecemeal, the engine might just be bare-bones and expensive to put back together. But if it is complete it will probably add up to a good package deal.
If the engine was running when it got hit and the guy stored it in a dry garage it wouldn't be a surprise if it cranked right up and ran after some simple work. You don't have a location shown so hard to guess about the weather there.