Wouldn't a little heat help? Now that is heavy enough material you should been able to remove it in one piece. I have remove things like that without even hurting the crankcase seal.
Here I have pulleys that refuse come off too especially drive pulleys on Cub Cadet ZTR where they apparently didn't use anti-seize either. Either that or just plain poor quality metals. With the bearing separators that have I can't break the rust seizure even I can get to the separation point. They so seized that I end up destroying the stamp metal pulley in the process. It takes lots of heat, the puller, and a high powered impact gun to even remove the pulley hub. If it was machined pulley I most likely could get it off without damaging it.
So much force so that l illiterately stripped the forcing screw. Now of course it was a cheap Chinese puller setup from Harbor Freight. I got a new American made forcing screw and had the upper puller bar re-machined for the new larger screw and haven't it out yet. You notice I said "yet". Give me enough time I probably strip it too but I think any other country made forcing screw is probably better that Chinese one except maybe one made in India.
