When I run 1/4 mile I am up at 138 with mine. The rear of the hood lifts 1.5-2". I may end up having to vent mine as well. At one time I thought about adding an air pan to the carbs and sealing them to the scoop, but with no where else for the air to go, I was afraid that it would pull it off of the hood.
I did the same thing on my 67 belevedere w/ a 66-67 superstock scoop. I installed a hood pin in the rear center of the hood and pretty much stopped it===3 on each side.