Ok, I need some advice on something. Found a motor for my track only 848 (I spun a main on my bike). Guy sent me the receipts from the shop and the shop is very, very reputable (from FasterTwins in Virginia. Seems to have a great reputation, no question on the build). Paid over $5000 for the engine build including upgraded main bearings, etc etc. He's getting a divorce, selling everything. Motor has about 300 laps on it. How do you buy a motor with confidence?? Shipping isn't an issue, just purely want to make sure I'm covered after we exchange money for goods and that the motor doesn't grenade after a lap.