Heres another trick
8mm bolt, cut the head off it and put a slot in the top with a hack saw.
Handy for putting motors on and of bases. Not so good for the later ones wit hthe long bolt behind the muffler as you need to use a different hole.
You can also clamp the bolt in the vice and fiddle with the motor, good for testing spark if youve had it flipped over on the bench messing with the coil or coil lead.
Doesnt matter if it gets a bit trashed, its easy to make another one.
This trick works for most mowers.
Trusty block of redgum. Set the height lever so its straight up and down. Tip the motor sideways and rest the height lever on the block of wood. Works on victas and rovers and the like.