Not to start a huge debate but the very high stock rod to stroke ratio of a 400 helps it make HP way past the peak so yes they can rev very good. The short R/S ratio on a SBC prohibits it from makeing much HP past the peak HP. Also the average SBC head will not flow 220 CFM, mabey some of the odd ball ones will come close OOTB but not your average head. Most all BBM heads from 67 on will do 220 easy. 220 is not huge but combine it with a exagerated high RS ratio and that is how they still make power at 6500. If you want to compare a odd SBC head to a BBM head you should compare them to a max wedge head to make it fair. BTW a small block mopar head flows as good as a BBM head. A stock magnum head can get 220 on most benches.

As for the whole quench thing, I am a huge proponent of useing it whenever possible, however it is not mandatory to make big HP so don't sweat it, quench won't kill your build. Personaly I would use the step dome KB pistons if I could not find 915 heads or afford aftermarket closed chamber heads.