There's no real difference in the LS1 and LS6 blocks apart from some thicker webbing in a few spots. The
oil control all comes down to the different design of breather the LS6 uses in the valley cover. The LS1 and LS6 valley covers are interchangeable so that's an easy fix.
On top of the springs there's a set of titanium retainers and hardened pushrods. The springs come with their own spring seats seat as well. The stock hydraulic roller lifters are fine as are the stock rockers. the stock rockers are a steel roller fulcrum rocker anyway so there's not much to be gained in going to aftermarket rollers.
Cheers