340 six pack hood closing clearance?

Edelbrock used to have something on their web page that compared intake height for all of their manifolds and stock intakes. That should tell you the difference

By the way there is no factory 6-pack hood for a Demon since Chrysler never offered the motor in an A-body. Mr. Norms refitted 6 pack intakes on their GSS cars and got them to fit... Are you referring to an aftermarket fiberglass hood?
Even the scooped hoods were no different than a flat stock hood except for the holes.