OOTB Stealth vs Prepped Stealth?

Hmm... I was thinking about saving up for Trick Flow heads, but for $2000 they will also need checked/prepped. A pair of Stealth heads is $1000 plus $600 for your work, and I think 300 cfm would do great on my 451. (I already have a new set of Comp dual springs for my cam). That's all the flow I'm likely to need in a street/strip car - isn't that enough to make 600 hp?