Lots of cams and even more opinions. Something around a 216/220 will give you pretty good torque, something around a 224/224 will cost you some torque but gives great mid-top end.

Allen Nelson (site owner) is a Comp dealer.
TRT Performance can get good deals on cams.
Thunder Racing carries the popular 224/224.
You can also get them used off the different sites.

Use the 'Search' feature on this site and others (performancetrucks.net is a good one) - there's a TON of information and opinions. One thing you have to decide is where you want your power, if you're going to go to forced induction, etc. Once you figure that out, you can go from there.