Yup. The problem is when the stroke gets that long you are out of plenum volume and out of runner. You lengthen the runners and you give up plenum. You can put a spacer on it, but when I tried it, It was a nightmare.
The problem could simply be, wrong intake. This is normally the issue when you try and use a Performer, Torker, Street Master, Street Dominator etc.... on a hot and/or a big engine. The Super Victor should be enough IMO. It is a hell of an intake. Best for the application? IDK. Wish I could help there. You need ether a "Been there and done that guy" or money and dyno/strip time to test the 2 intakes. IF you can afford an intake purchase just to cut up, weld on, grind on, great. Not my suggestion to do, but if you could and didn't mind......