First let me say that I am not an engineer and I don't pretend to be one. Most of my structural integrity lessons were learned in the school of hard knocks. So this is just food for thought and discussion. I be really interested to hear what Caleb thinks about this.

I'm not real good at putting my thoughts to print, so I will spare you all my efforts to do that and just tick of some points and ask some questions.

The cabin frame in the 750 has a single diagonal bar on top.
Is the diagonal there to brace against prop torque or P-factor?

The Corvair spins opposite direction of most standard A/C engines.
What effect could this have on the airframe?
Would it make a difference if the Corvair engine is the 100HP or the boosted 120HP?
If this is an issue should a Corvair builder be consider adding a diagonal the opposite direction?
Or would the factory consider welding cabin frames specifically for the Corvair?