Increasing brake torque by using a larger diameter rotor is only one way to increase braking.
Adding larger surface area to the pads and clamping power is another.
I will point out that the system that I went to, i.e., using 67 Ford T-bird fronts and 65 Mustang front's on the rear, double the braking capacity of the Pantera, and fit within the original 15" Campi's.
The components are less expensive, readily available and are durability proven run on the Ford factory Mustang Trans-Am cars in the 1969-70 Trans-Am racing season. They are still being run today in Vintage Racing.
They are very easily adaptable to the Pantera and only require installing an adjustable proportioning valve for the rears.
Using the Tesla EPB conversion solves the parking brake issue and it permits you to remove permanently the cabin handbrake and mounting structure to the passenger seat area.
I don't know why so many search for exotic solutions to better braking? To me this is as obvious as the nose on my face, which admittedly is very prominent. 
