My 37 Chevy pu has a 302 GMC,3.36 gears and a Saginaw 4spd with an overdrive unit.2000 rpm in OD fourth is around 70 mph.The truck doesn't slow down on hills at all.My wifes 51 Chevy pu has a mostly stock 261,3.40 gears with a NP883 4 spd OD tranny.2000 rpm in OD is around 67 mph,same story on the up hill.Both these trucks can pull a 1200 lbs travel trailer in OD no problem on relatively flat roads.
Maybe in hilly areas more gear might be necessary with a heavier truck
Personally,I think a 3.50 or so first gear with lower than 3.08 gears is a pain in normal driving,first gear winds out too quick.
