I agree with the brand of cobra. I had to plane down the carb. surface of my Vic Jr. .0250 to fit under my LSC cobra. I think it also depends on the height of the hood scoop. I know my 2000 LSC cobra is shallower than the newer car they put out.
I can't use a turkey pan because it hits the hood up front.
Put a straight edge across the block valley and measure to the front of the hood and back, as it of course slopes.