A 4" or 6" two leg puller is the only way you will get that off.
You need a bolt thats longer than the old one by the length of the height of the boss.
As Grumpy said, you need the puller to hook on the top of the boss, not the plate thats welded to the bottom of it.
The motor you get as a replacement, theres 3 shaft lengths that are comonly used, the one you need is the middle one. Its about 62mm or something. If you can only get the longer 82mm you could space the motor up 20mm with three spacers.
Tipping the mower over that way, do you do that often??? That will make it smoke.
