I'm good at making people's heads hurt.
Seems to me you can either:
1) Go with the safe 3.45, and worry you might have saved more fuel with the taller gear, or...
2) Go with the less safe 3.27, and risk feeling like your truck accelerates too slowly.
I expect the 3.27 will be fine, personally, but I also have
very low expectations on how a vehicle should accelerate.