I by all means dont want to open the engine up to 2900rpms for a long period it sucks fuel now as it is without any load. Alot of my friends stick with 4.10s in thier 10 bolt and have no issues. Looking back at the gear ratio calculator, 3.73s with 31s would almost be the same be it a 4.56 with 37s both doing 70. My only option for solving any sory of high rpms at 70mph would be to find a tranny with autodrive with low miles or convert it to a 5 speed stick, which at this point in my build would not be all that hard
Well my question would be how much road driving will you be doing with this truck, city and hwy? if this truck was going to see trails some or a few times a year but be a weekend warrior to cruise and have fun then I would stick with what you have now with 37's. But if the truck is tore a part swapping in a built 700R4 or doing a 5 speed swap would be easier now then later, I guess it depends on how deep your pockets are and how much work you want to do.