Per Member Joe H
and a list I concur with. Although JoeH's list in my opinion would be the end all be all 6.0 upgrade as it would require pulling the motor to complete. I would also change the small rotating bits at the same time like idlers, vaccuum pump, ect, ect, ect. The thread can be found here:
Here's what I would consider the full meal deal on a rebuilt (or bulletproofed) 6.0 powerstroke.
-ARP head studs. That means the motor has to come out.
-Heads. New or resurfaced and were they o-ringed?
-HPOP. 2004.5+ not known for failure but ask anyway
-upgraded one-piece snap to connect HPOP fitting
-Dummy plugs (upgraded parts by Ford for injector health)
-Standpipes (upgraded parts by Ford for injector health)
-EGR cooler with the round tubes or BPD cooler or an EGR delete.
-injectors. Original or remans. 100k is when they start to go.
-New oil cooler. OEM and not a Dorman.
-water pump. Go BPD or Dieselsite for the metal impeller
-upgraded turbo oil fill and drain pipes
-upgraded alternator and fresh batteries
-coolant flush and Ford Gold replaced with a CAT EC-1 rated ELC coolant
-new charge air cooler (CAC) boots
Hope this helps trigger ideas for you.