Finned vs smooth brake drum

"also told me I have to get rid of the back seat belts".
Another case of stupid laws enacted and enforced by those that don't understand mechanics or physics. I could see not allowing bigger engines in a chassis that wasn't designed for such, but to not allow improvements in safety items like F-kin seat belts or larger brakes. Probably cant add a 3rd brake light, or halogen headlights either.
I would argue that it "pretty much" left the factory with drum brakes. As said, I doubt a swap to 10" would get noticed. I'd give it an attempt anyway.
Did 63 come with dual circuit master cylinders?