I'm looking at the same (512 with Sniper) for my 68 Charger. I know this is apples and oranges, but on my 69 GTX with RB engine and air grabber a Holley SD fits with stock hood but just barely. That has a Proform Carb on it though which is higher than the Sniper. I think about 3/4 inch more room with a B series engine. I don't know how much difference in under hood clearance between B body and E body but I would think it would be about the same. In my case for the Charger the Holley SD currently is at the top of the list for stock hood.