9in drum brakes

Pishta,
A disk brake IS a G clamp. Very naieve to think that the open end of the clamp doesn't flex some, even if it is only 0.003-4", it becomes lost clamping force.
Obviously you can improve any braking system. With discs, use a bigger piston. Same with drums. The Bendix duo-servo drum brake is a very efficient braking system that creates a wedging action of the shoes, improving the braking action; something that disc brakes lack. Discs rely on more line pressure. This pressure discrepancy was why we got proportioning valves when discs first appeared on the front wheels. They need about 50% more line pressure to provide the same stopping power as drums, so the PV was added to reduce pressure to the rear drums & prevent lock up.
The Bendix system has been around for decades. My 1948 Olds had it.