Flywheel for Slant Six and 833 4 Speed??

You have another option. If you're just dying to spend unnecessary money on a new one, get one for a 318 and slot that last hole to line it up. It works fine. Lots of people have done it.
Not going to work...slant 6 flywheel he is asking about is 122 tooth ring gear, not 10.5" 130 tooth.

The only new flywheel available is billet steel, and not cheap. If you have a good wheel, I would just grind it and roll.