The price quote you've received on rebuilding the 216 is approximately twice what the cost should be. The 216 is difficult to rebuild, but by no means impossible or that expensive. Most shops want to do lots of modifications because they don't know how to do an original type rebuild. There's still a few of us old geezers around who remember how to do the job the right way, the first time! I'm working with a young man in Oklahoma to help him rebuild an original 1953 235 engine in a 2 ton truck his grandfather bought in 1955, and it's still working for a living hauling grain. I'm also advising a man in Virginia who is rebuilding his first Babbit-rod stovebolt engine and putting it back in original condition. I'd suggest that you shop around a little more for an engine builder who won't rob you like Jesse James!
Jerry