Thinking outside the box

GM ls2 engines come standard with the cathedral port heads that I imagine flow good numbers for a stock head. They now have an ls3 6.2 motor in the 08 G-8 sedans that have a stock tall port head with 2.16 int and 1.59 exh valves, and they flow close to or over 300 cfm out of the box. These can be had for under $400. ea