Ok, friend calls and says his 40 horse, four cylinder, Tracker Pro Series engine rattled and locked up. We pulled the spark plugs and tried to turn flywheel and no go. Using a screwdriver in plug hole numbers 1 thru 3 move in and out a little bid while wiggling the flywheel, number 4 is stuck solid. He said it was running the best and stated to rattle, then quit. Short story long is, there is a 50 horse, four cylinder stripped power head on ebay for $350, my question is, if I buy the 50 horse, am I asking for trouble by using the 40 horse carbs and electronics on the 50???