NPI vs PI heads under boost...

I'm about to go nutz deciding whether to go with boost or juice. Ok, first I want to know about NPI vs PI heads under boost. I know everyone says keep the NPI heads if I get a blower, but I always thought that they meant to save money. Well I don't care about saving money, I want to make power. I'm getting a new SB from VT for sure...should I have these stock NPI heads worked and reuse them on the new motor or would it be worth the time versus just buying VT's PI longblock??

In short, how much more power will the same Boosted motor make with PI heads as opposed to NPI heads? If I'm lookin at a difference of less than 30 HP at the wheels then I guess I'll just slap the p/p NPI's on a new SB...