5.3? The 212 218 (@ .050) from comp is the biggest I'd go, otherwise you are going to have some loss in the lower end. Vinci also has some torque cams for trucks, and there's always custom grinding.
You'll also need valve springs and hardened 7.4" push rods. Most manf.'s grind their cams on the factory base circles, so 7.4" push rods are used. Lingenfelter sells LS6 valve springs that are $50 and will handle mild cams with less aggressive lobes. I'd also get new valve seals, water pump gaskets, possibly valve cover gaskets in case they get damaged, timing cover gasket might need replaced too. Also you will want a new timing chain. That's all I can think of off the top of my head.