I cruise all day long at 60mph with a 216, 3spd, 4.11:1 rear end with a torque tube.
One of the keys to that is not to put dinky small diameter tires on the truck. I put original style 16" rims with large diameter tires ~30" . 225/85-R16 is the closest modern size to original bias ply.
My wheels are the original 17" artillery wheels. 29" diameter according to Coker, so not small. So it sound like with overdrive I wouldn't need more gear.
