first of all DO NOT waste your money on that POS pro. products intake, it looks nice but its a peice of garbage, i tried it 2 times for customers and both times we sent them back, they dont use the factory style o ring gaskets, they use a flat old chevy type of gasket. it will leak like a SOB, toe port alignment on the manifolds and the gaskets are terrible, your asking for big trouble with it, go with a bbk if you want an aluminum intake or stick with an ls6, im an FI guy so I would say 60s. there not going to be much more money then any other size and there very easy to tune still and no mater what you do down the road you will never have to get a bigger injector unless your going crazy like me. 430 with a m6 is realistic, what is your compression? how much you drive the car will be a factor in how big of cam you go with in my opinion. also if your planning on going with NOS down the road you should factor that into your cam selection now