Does anyone have a method of cutting the center out of a magneto flywheel for using it as part of a 2 part prop hub that won't ruin the fit on the crankshaft? I tried a few things like a hole saw without any luck, my flywheel is 5/8" thick where I need to cut thru it. Is it possible to maybe make a tapered mandrel to mount it in a lathe? The engine is an older Stihl about a 25cc. The part I am trying to save resembles a larger Supertiger prop drive which I want to use for my magnet mount ring.
If there is an easy way to do this, I'll try it. There are already two threaded holes in it to mount the second half of the prop drive which I can machine on the lathe. Any ideas? I can provide a picture if needed.

Thanks for any ideas you may have.
John