if you wanted a true functional ram-air scoop, i would look at a 67, the 65/66 scoop sits too far back, and too low it be in the path of pressurized fresh air.
however, by sealing off the scoop to under hood pressure, the scoop will still draw cooler air from outside the engine compartment, just wont be pressurized... like a "ram-air" set up
i actually sliced and diced my "real style" gt350 hood(metal understructure) to raise the scoop opening about 1" so the opening didnt look "small".
mine has a closed cell foam "pan" that seals it too the bottom of the hood, the air cleaner is inside the pan. i seriously doubt it made any gains at all sealing it off, but it sure does "look" functional when ya pop the hood..... the pan also hides all the NO2 components nicely.