How you are going to use your truck determines its power range and the parts you use. Normally aspirated engines have about a 3000 rpm power band. You have to choose where that range is. 500 to 3500 rpm, or 1000 to 4000 rpm, 2000 to 5000, or 3000 to 6000 rpm or somewhere in between?

A U-Tube primer on camshafts:
http://www.youtube.com/watch?v=bnfdYc2GAz0&feature=relmfu
http://www.youtube.com/watch?v=gqerHlVIqS4&feature=related
http://www.youtube.com/watch?v=46GR_iHJx-k&feature=related
http://www.youtube.com/watch?v=Pa3mKXN-tIY&feature=related
http://www.youtube.com/watch?v=MRHm5eTBnpA&feature=related

One of numerous explanations on camshaft specifications:
http://www.hotrod.com/techarticles/113_9604_choosing_the_right_camshaft/viewall.html