TSP 228R cam and a small stall work quite well with a 5.3

 

Being a nnbs truck, you should already have the 243/799 heads. Those are already good flowing heads. IMO i would mill them to bump compression up a little bit, use the money saved from buying heads and buy a quality set of longtube headers and exhaust. Does your truck have vvt or dod? Now would be the time to replace those dod lifters with some ls7 lifters if you are dead set on head work. A 212/218 or a 216/220 cam with a 3000-3400 converter (9.5" not an 11" tb verter) would be a nice combo

 

dang it didn't see the nnbs part. Youll have to do a dod delete to run any of the older 3 bolt cams.

 

212/218 112+4 high lift
Pac 1218s
Long tubes
4" cai
Ud crank pulley
Yank tt3000 or circle d 3200 converter
Custom tune