308 or RHS on a 408

Going through my RHS/Indy head links, I see that Brian notes that these heads "have incredible intake port speed" on his website.
http://www.immengines.com/rhsheads.html

Obviously, a good trait. Perhaps my conservative tendencies leaned me too far over!:p
Since I've offered as much opinion and info as I can for this particular combo, I'll sit back and hopefully learn more about the heads myself.