If I want to keep my heads, lifters etc... stock but get a better cam in there, what cam should I get? I see they provide gains of 40hp and improve the powerband. Any suggestions?

 

Most cams will require the installation of new springs and while you're there you might as well replace pushrods. As far as cam selection goes you might try thunder racings website. They have a pretty good selection of cams and dyno graphs to go along with a few of them so you can see how your car might react to them.

 

Id finish your bolt ons first (headers)

 

You might consider Thunder Racings TR224. It is probably the most well proven cam for an LS1. Excellent power increase, good lopey idle, no major tuning issues. You will have to use a set of high performance springs on any high performance cam regardless of brand. Most people just use a set of Comp 918 springs. No machining is necessary and you can use your stock retainers and keepers. While hardened pushrods aren't required, you should replace them when you change your cam. If you don't, just miss one shift and you will have to replace them anyways because the stockers will be bent.