While having tension on the flywheel applied with the puller, try hitting the crankshaft smartly with a hammer. If the puller has a bolt centered on the crank, just hit that bolt head. if you have to hit the crank itself, thread a nut on the shaft so you are hitting the nut and not the shaft threads. Since you have a heat source, maybe heat up the flywheel to expand it and then hit the crank. This approach has not failed me yet. Good luck.

Richard/Club Saito #635