most of that stuff is relatively easy to do with ls1 cars...i did the headers/ypipe pretty much by myself except for lining up the egr & ypipe to Ipipe connection on new years day...cam swaps can be done with the heads on the car though spring swaps can be a pita without the right tools
Personally I'd say do the stuff yourself as its a learning experience and just being able to say you did the work yourself is worth more then a slip in my page. But JW is right on with all the prices, but then again $350 is about what a set of coated Lt's would cost so id rather do the cam swap myself. But thats me.