For one more data point for the OP to consider...my 408 has a 264/268 solid flat tappet cam with heads that also flow 293, and I use a home ported Victor intake. Although I have never dynoed my engine, my ET/speed/weight say that my car is somewhere in the 580-600 hp range (depending on your calculator). Granted, I don't think that is all from the intake as my 408 is 13:1 on e85, but I'm pretty sure some of that number is attributable (how much I could not tell you). My 408 does pull very hard to 6800, which seems to be the sweet spot for this engine for best ET...and it does continue to pull hard WELL past my comfort zone.
