If you did the water pump and opti by yourself then you where already half way there. The biggest thing is that you have to feel like you can do it, do a bunch of research so there isn't any surprises during the install. I believe your LT4 springs are good up to .525 lift, so I would recommend the CC305 cam to you. It is a little hotter than the hot cam and it is very streetable, I currently have it in my car. The specs for the CC305 are 220/230 .510/.510 114LSA wich means with a 1.5 rocker this cam will work with your springs. This cam has a nice little lope to it at idle and power throughout the entire rpm range. My engine currently has bearing proplems (not caused by cam install) so when my new shortblock gets here I am going to install a CC503 cam. I wanted something with a little more lope to it, this cam would also work with your current springs but I don't know how your speed density would like it. Since you will be shifting at 5500 I think a CC305 would be perfect for you. Good luck

Also from what I have been hearing anything bigger than a CC305 requires a stall, so keep that in mind. I have an M6 so I don't pay to much attention to stalls

 

You can easily get a cam install done in one evening, if you're just doing a cam and you know what you're doing. But, while you're there, I'd definitely do a new timing chain. It'll be time to change it soon anyway, and if you're going to run a bigger cam you don't want a stock sloppy timing chain that's on the way out. You'll also want a gasket pack, there's no good reason to reuse old seals when it's a 5 minute job to replace them.

The problem areas are finding tools to remove the crank hub and crank sproket, and reinstalling them. Other than that it's pretty much smooth sailing.