That's not going to tell you anything either. I've converted a bunch of engines and haven't seen a ROUND flywheel yet (OK Ralph, except on Zenoahs). On my Toro, I mounted the flywheel on an old crank and turned the boss on the back of the flywheel round so it would be running dead true to the crank and while I was there I went ahead and removed the fins. Now, with the boss on the back running true you can mount it in your chuck and face the front and bore the hole so a normal size prop hub can be used.