How to remove stubborn tapered shaft

I was going to suggest applying some gentle heat to the inner hub of the pulley with a propane torch, but seeing this thread is a few days old, I assume you have shifted it by now?

BOLT-OFF, the Landy owners friend (in a blue spray can)

I pull stuff like this to bits often mostly chainsaws. Put the nut Back on to start with to protect the thread put some tension on with your puller and a little heat if you want put one hand on the puller making sure the engine is hanging in mid air ie suspended by the puller and give the puller centre bolt a solid whack it should come easy enough I haven't had one defeat me yet.