Hello and welcome to OB. Can I make a couple of starter questions/suggestions:
Put your truck details in your signature, with miles, options, bolt-ons, upgrades, etc. This information, in the immortal words of Jerry McGuire "helps oilburner folks help you".
Secondly, since you are working on a 6 liter, do you have a tuner or any kind of ability to monitor the ECM? Personally, I think you need to look at the oil versus coolant temp number before you do anything. It tells what I think is an imperative story of the current thermal conditions of your truck.
Just my .02 worth, but if you can get a steady state temperature delta I think it will help your diagnosis.
Good luck and again welcome to the forum.