Need help on gears for my 87 R10 and new 383

[UATahoe]

I am about to install a 383 motor into my 87. It has a 700r4 tranny and the current rear is an open 2.73. I will never be racing the truck obviously and gas mileage is my min concern but I read a few posts here where people actually gained mpg going to a 3.42 or 3.73 gear ratio. Given the new motor and additional power should I change the gearing or am I going to get the best mileage out of the 2.73's? Thanks for the input!
Posted via Mobile Device