I have a crank "straightener" up in the attic of my garage, works real well. Check with some of your local guys, they probably do as well....
It doesn't really straighten, but rebends the crank in a different spot and the blade cuts level, and the vibration is gone.
Most dealers put them away when the world was taken over by lawyers, but if you brought the engine in off of the mower,
and paid cash, etc... They could fix it for you......On lunchbreak, etc....