He already has Edelbrock heads that will easily go over 300 plus cfm with a little work. Edelbrock Victor heads are a very expensive upgrade. Get a little more flow out of them and maybe step up to a 1.6 rocker on the intake side
I must have missed the post where he says he already had those heads.
No they will not go 300+cfm with A LITLE work that takes alot of work and a boatload of knowledge.
Sure RPM heads can reach 600hp on a smallblock mopar,but its certainly not within their intended usage.
Do it with a better head and end up with a much happier engine,unless you just build a good 500Hp engine and then throw nitrous at it to get to 600.