[Pyrotechnic]

Any way you can rig up some kind of test stand? I've seen people stick the oil pan in a sturdy tire to support the motor and splice a garden hose into the lower radiator hose. A car battery, a gas can and some fuel line, and you can run it for a bit and make sure there's nothing obviously wrong with it. After you've heard and seen it run and it's to your satisfaction, then you can feel a lot better about spending more money on it. To me, this is best test for a junkyard motor you know nothing about.

I wouldn't go as far as messing with the bearings though.