Back when I had a 2017 5.0, I re-geared from 3.31 to 4.10. It was a huge difference but please make sure you have a reputable shop do the work. It wasn't long until I had issues in the front differential. Something wasn't installed right and came loose. Had to replace the differential all together.
How is it with the 2.7 and those tires? You mentioned the MPG drop but how much? Still have enough power around town/etc? Appreciate any commentary on that. Looks great and dang near exactly what I want to do.