Highest flowing sbm heads?

My goal would be a 600+ hp 4" stroker based engine that I can take to the strip occasionally and mostly be obnoxious with around town.

I figure in round numbers I probably need upwards of 310-320 CFM to get to those power levels on a fairly optimized tune and combo. Just from the research I've done. Some guys here have actually done it and I'm appreciative of their knowledge and advice.