A janked up key is either from the flywheel slipping or carelessness installing the flywheel.
Whn the flywheel taper matches the cank taper right and it's torqued correctly, technically you don't even need a key.
Get some valve lapping compound from the auto parts store, dab it inside the flywheel taper and work you hand back in forth and around while pushing the flywheel on.
Pull it off and wipe it with a rag, repeat, repeat, repeat.
You will know when it's enough by the whole inside of the taper as well as the crank taper being the same dull sheen.
Brandon gave me tip for monster HP motors that doesn't apply to me but since were here, heat up the flywheel taper with a torch then install.
Obviously not glowing hot but around say 200-250 degrees. Once installed and cooled down they will be married.
I didn't do the torch part. I'm paranoid about gettin the flywheel back off which I had bad luck with before.