This is just my opinion so take it for what it's worth. I wouldn't pay that price unless it had current electronics - radio, gps, depth finder at the least, a full set of curtains, and a set of cushions in decent shape. This is after passing a good hull survey by someone experienced with Grady's.
You didn't say what engine is in the boat but presumably it can be replaced for under 8,000 with a shop doing the work. You could probably do it yourself for around half that. Not sure what a rebuild would cost but would probably not do that myself.
Based on the postings I've read here over the last several years, it's usually a lot more expensive than expected to refurbish. I'd probably plan on 20k by the time he gets a trailer and gets it the way he wants it. Again, just my opinion.
Gary 89 Overnighter