I think on the right engine that intake would make a difference. Ideally an aluminum head engine where you can really separate the engine heat from the air charge, and in a situation where the air intake is drawn from a cool source like cowl induction or a scoop.
Honestly the best part about the Air Gap is that you can run vacuum lines or wiring under the runners to help clean things up.
I seem to remember that with the right carb and air cleaner the Air Gap would fit just fine under a stock hood. I don't think it's that much taller than a standard Performer.
I replaced my Performer EPS with an Air Gap. It is much better with great mid range response and more low end torque. It was worth the money and hour it took to install. It does clear the stock hood, it's close but clears with a Holley 770 carb and GM performance drop base 14" air cleaner with a 3" K&N element.