Well yeah, they are, but lets face it, he doesn't need a blower to make 500 HP with a 454.
A 10:1 motor with the right cam and a set of Dart 275 Oval Ports will make 500 HP. That will also be a heck of a lot cheaper than a blower setup.
If he wanted to plan for the future with just a cam change, I'd buy the Pro1 310CC heads.
http://www.summitracing.com/parts/DRT-19100112/