5/8 ton gear ratios?

[woodie70]

i was thinking about changing out my r&p to gain some drivability on the highway.... 70' 5/8 ton, 350, two bbl, 3 speed.... should be 3.73 from all my research... wondering if any of you have done this and have any suggestions.
was thinking 3.08 or 3.38.
i am in the process of building a 90 350 2 bolt now, all stock engine converted to carb.... if i do that and go 350 turbo for tranny would that warrant me choosing a certain ratio.. not building a hot rod, i just drive it every day for now. thanks chad