I can easily cruise at 60-65 mph (around 2300-2500 RPM) on a modern highway: high pressure 235/261, with wider diameter radial tires on original wheels, and 3.55 rear end.
I will not tell you my top speed (for short durations - not a cruising speed) in my 1954 enclosed driveshaft Suburban with a 270 cubic inch 261, and one two-barrel GMC 302 carburetor with adjustable jets. It is 20-30 mph over the speed limit.
