I've been thinking about this combo, too. It's usually not too hard to find a non-running 317, CHEAP. I think as M18 or M20 would be an excellent engine. They are built like tanks and have a magneto ignition, making them nearly idiot proof(and I need that). That magneto ignition requires grounding instead of power, so you can't just plug it in. I used a relay set-up on my Magnum ignition K341.