I really liked the "shot in the dark", in fact thought it was an excellent reply. I have a car with seemingly "miles of vacuum lines", under the hood, across the front, under the dash and yes even to the rear deck. Any guesses what it could be? No matter, point is when it is not running just right, I start troubleshooting the vacuum lines and components.
OK, now for a longer "shot in the dark", time for the flood lights kind of dark. I picked up on the phrase "old boat motor". I don't know if it is true, but I've heard boat motors have a different cam and they run backwards. That could put you out in the weeds if trying to time it as a car/truck motor. But if the motor was running backwards, wouldn't it have only one forward gear and several reverse gears? Perhaps, it has been converted to normal rotation, yet the reference points are misleading.
Hopefully, this will be more than a big laugh. Someone may pick up on my thought.
My thought...with respect. Comb the swap meets, Craigslist, want ads and junk yards, a running 250 has got to be less than your current investment and time on this project.
Good luck.
