I'd go $10K and tell him to keep the 396 and sell it to someone else. Then drop a GM crate 350 or 383 in it and have some fun.
Seriously though, does the car come with a trans, bellhousing, and new clutch, dirvehaft, everything to make it driveable? If the car is solid, you are starting to approach where you could almost get into it and not lose anything if you have to sell.
I sort of doubt your estimate on how much it would cost to pay someone to put it together, because it looks like more than 60 hours of work to me, but if you could just farm out the bigger jobs and handle the small bolt on stuff yourself, you might be in the ballpark.
A frost green, 69 Camaro SS 4 speed car is a nice ride, small block or big block. If you have the cash and aren't worried about finishing it and having to sell it in a year, you probably won't lose money. They are only going up, and there are more than a few of us who thought a relatively short time ago (10 years?) that $10K was steep for a running, driving big block first gen. Now I think all of us would buy as many as we could get at that.
I'm going to go back over your posts from the beginning and see if I see any big ticket items missing, but I think you're getting really close...
