Wanting to install a cam
A lot of guys here will probably suggest a 224/224. Many companies sell variations of or near this cam-intake/exhaust duration. From what I hear, it's a great daily driver cam, yet yeilds impressive numbers when set up and tuned correctly.
If you haven't checked out the "Cam Guide" sticky atop this forum, I strongly suggest reading that. Springs, pushrods, an oil pump and new timing chain are great things to buy when doing a cam. The only thing capable of being "dropped in" as simply as you stated are the pushrods. I wouldn't want to attempt any other, especially a spring swap unless the heads have been removed.
If you plan on installing the cam yourself, LS1howto.com provides an excellent write up on every step of the intallation. It's a good thing to consider, especially because you won't have to pay anyone to do it and you'll also gain some awesome experience, and I frankly feel like I know a lot more about the motor after doing it. The best of luck to ya! Hope this helped.
Rick M.

