I would definately run the 308 heads, or better yet try to get them to let you run magnums, the chevy guys will probably run vortechs.

Are you allowed to port the heads? If that was legal then a 302 or 920 head with 2.02 valves may work good, you can get plenty of flow to keep up with the 2bbl, sorta how the NASCAR guys run smaller ports on there restrictor motors. Also since it is a closed chamber head you can get some quench with out a reverse dome that makes dead space in the chamber, those two things together should give you lots tq outa the corners.