Ron, I suppose it's possible the small NACA ducts could cool the brakes but comparatively speaking they are far less volume than the normal ones on either side of the rad opening.
I'm glad you brought this up as I think it's an important issue. Many are worried about having the largest brakes possible but not worried about keeping them cool.
After you get to a certain size bigger brakes do not yield better stopping because of the tire contact patch limitations. What bigger brakes do yield is better heat resistance. Why can't you improve heat resistance with better cooling, and keep the weight performance edge (rotating, unsprung, overall) of smaller brakes?
This is a fix that's good for anyone on a budget that's not unlimited in that it's achieved with just fiberglass materials and labor as opposed to purchase of expensive larger brakes.
Not arguing that the largest brakes possible don't have their place, just that it may be limited except for the most competitive instances and then only on certain tracks.
I do remember reading that some of the original GT's had issues with overcooling and they ducted through the radiator to moderate temps. It would be interesting to read the SAE article on the subject. It would seem to be an issue of rapid heat cool cycles causing damage but I would think you could adjust it merely by restricting the air intake per conditions.
The ducts I designed use the original intake location. They are glassed to the inside of the front corner light covers (inside fenderwell).
The first pic is of the forms stuck onto sticks preparatory to laying the glass. They are constructed from building insulation styrofoam, covered with foil and waxed with mold release(not enough). This stuff cuts easily with a hack saw blade without the handle and body sanding boards with 36 grit. The hardest part was the round piece, made separately and glued with spray glue to the main body.