Not sure but if you push the motor beyond it's limits it may not hold up long. Especially if you don't re-build it. You'll have to make an adapter plate to re-position the carb, as well as for the rectangular exhaust flange. Personally, I'd keep the old lawnboy intact. If you don't really want or need the mower, sell it and buy a good, used side-shaft Briggs. Good luck.