Your scenario reminds so much of my experience with the oldtimer that did my work. I called him a POS in his face, and according how you've been treated it seems your guy would qualify for this name. There's just no reason anyone should take 6 months to get parts and put a motor together. Did he tell you ahead of time it will take 6-12 months to do the work? Its always easy to make suggestions after the fact, but you can't really trust anyone and one should have L/T and labor/part cost in writing. Had I done so, I would have won my case. I did end up taking him to small claims court over excessive L/T time and charging 3x what he agreed to (nothing in writing though, just a man's handshake). Sad that the world has become this way. Hang in there, demand a completion date from him.