I am not sure of the correlation, but with a turbo 400, 37" tires:
RPMs at 65 with 4.88 are: 2900 RPM
RPMs at 65 with 5.13 are: 3030 RPM
RPMs at 70 with 4.88 are: 3120 RPM
RPMs at 70 with 5.13 are: 3260 RPM
EDIT: so what I am trying to say here is if you want to drive this truck to town or down the interstate to a show or to a mud event, then that high of gear is not going to be good with 37's. IF you want driveability you are going to have to give up a lower gear ratio so you are not turning that engine at 3000 RPM, it will not last long or like you, but love the gas station.