[JLMounce]

Street application? Probably minimal. I believe I've read before you run something like an s480, is that correct?

That thing will probably make every bit of 1100 hp...to the tire, at about 15 psi on an aftermarket headed 455, regardless of what head is on it. In fact, I'd bet it would do it on a set of as cast D or round ports if you push the boost up a bit.

I'd be more worried about a factory block holding together than I would be concerned about which port type I'd be using.

That being the case, something like an SD 290cfm KRE D port with a properly sized cam in a normally aspirated 460" Pontiac will typically ring the bell between 550-570hp. With something like an s480 pumping an additional 14.7psi into it, you're in 4 digit hp territory. Knowing you already have D ports which your hot side is designed around, I'd do either the Edelbrock D port or the KRE D port, which my preference leaning towards the KRE product. I don't believe you're going to see noticeable gains in a street application with a round port to make the hassle of redesigning your hot side worth it.