I would shy away from the GT-40 / Cobra intake for performance reasons. I had the GT-40 intake on my old 302 setup and it worked great...but once I stepped up to my 331, the intake couldn't keep up with the engines breathing requirements. A Trick Flow Track Heat intake solved all of that.
Since you're going to be pushing 500 HP, I think you'll find that there will be much more power to be found with a higher flowing intake.
The GT-40 intake is a great intake for mildly modified 302/306s, but once you get over 375 HP, there are better choices out there.
E