help with heads?

i have an ls1 gto and want to upgrade the heads cam and intake. i originally was going for the ls6 243 heads. after some research ive been seeing 799 317 and i think 842 or somthing? now i know theyre all better then the 241s i have but what are the pros and cons to the different castings and what are a better gain or upgrade?

799 & 243 are supposedly the same casting with the difference being the 799's have sodium filled exhaust valves. Both are 65cc. The 317's are the truck 6.0 heads and are 72cc and don't flow as well as the other two. I'm pretty sure the 842's are truck heads too, not sure on the details.