Stuck flywheel help

Heat will destroy the magnets on the flywheel but since you are replacing it I would try it. 

Might try removing 3 of the starter clutch bolts and getting a harmonic balancer puller and try pulling it off that way. Don't use a breaker bar for this. Use an air impact and tighten it down. You want a lot of tension, but don't hammer it down and allow it to get out of alignment. You want the center bolt pulling perfectly straight. Then tap the center bolt with a hammer a time or two. If it doesn't pop off, then retighten the puller and tap again. If it doesn't come off after a couple of cycles of this process, then maybe try a little heat. Not super-hot, just warm it up and try the puller again.

If this doesn't work, then may the force be with you, cause I'm not sure where to go from there.  

I think as long as you use propane or map and not oxyacetylene, and don’t get anything hot enough to start discoloring metal, you’ll be ok. The flywheel will obviously be heat soaked first before the crank, and it really doesn’t take a ton of heat to get the metal to expand enough to help you out. Think like 150-170F. The oil runs around that temp anyways.
 

Another last resort is a dremel and small cutoff wheel. You can go VERY slow, working perpendicular to the threads on the flywheel until you get close to the crank and have enough metal removed for it to expand a little and give you enough tension off of the taper to get it removed. Might be best to do it right over the top of the keyway for the woodruff key, so if you go all the way through the flywheel, you only damage the woodruff key and can buy a new one for dirt cheap. Sounds crazy, but I’ve used this in similar applications before and it’s worked. This is one of those last resort type deals. Again, you have to be extremely careful and go very slow to not damage anything you don’t want damaged. This method, along with heat after the cutting is done might get you out of the woods. Don’t forget to make sure you clean all the metal shavings and stuff up before you put it all back together.

Like mentioned above, but put the pulled back on and put 5-6 tack welds around it then tighten the bolt down some and hit it with a hammer. Tighten it down some more then hit it again.