Drove a 1935 Buick, 231 S8, 4.11, 4 hour trip once at 55
MPH and a 1950 F1 straight 6, don't know the ratio but
I read this morning that 3.92 standard and 4.27 optional.
Drove the F1 80 miles round trip to work for a year doing 65.

Never felt the need to change gears. So I say drive it stock
and see if it works for you. Jeffrey