A Motor repair manual I've got handy lists a 1955 235 passenger car engine as getting its peak torque at 2200 RPM. That's the general area you should shoot for to get the best throttle response at cruising speed. Max HP happens at considerably higher speed, like 3800-4200, depending on which model I look at, but that's only for pulling heavy loads at wide open throttle in the lower gears.
Jerry
