600 CFM, all I need. Check my math!

That carb is not too big. The math you are using has been proven wrong for decades. Yet people keep using it.

Your carb is a self adjusting unit. If it's rich, it's because it's not correctly tuned, not because it's a 750.

Second, I don't know how you figure 107 MPH is only good for a 13.9x pass. At that MPH you need to be running 12.6x-12.8x or something is wrong.