input on cam
You might want to install the headers first. There's a good chance, depending on what cam you already have, that the LT's will really wake things up. Also, if you already haven't, a little tuning might help with your idle issues.
Beyond that idea, before making your cam choice you'll want to factor in your future plans for cylinder heads. The resulting static compression ratio (SCR) as well as dynamic compression ratio (DCR) is a product of you H/C combo. It's an important factor to consider. If you make the wrong choice you could end up with a setup that requires race fuel in order to avoid pinging, or a setup that is far from maximized with respect to performance and drivability.
So what kind of heads will you be running and what would the resulting SCR be?
BTW, have you checked out the truck section? There's some smart guys with hotrod trucks over there that could prolly offer some good insight.

