Mitty,
Put the flywheel on a lathe and turn down the fins to the same level as the hub of the flywheel. If you are accurate, balancing should not be a huge problem. I have never considered disturbances caused by the flywheel being a problem - the reason you turn them down is due to weight saving measures.

By the way, mine works really well without "no dang electronic ignition"! It kind of defeats the purpose of conversions - keepin' em cheap! If you price an ignition system you will find they cost as much as a brand new weedy at Home Depot.

Good luck with your conversion projects. BE CAREFUL, you might become addicted!

Tom