Boulderado,
Yes, that is correct, with 28" rolling diameter tires. I have had my truck up to 70 briefly with the 216 and it is just working the babbitt pounder too hard. They really don't like sustained high speeds.
Tony,
Good point. I recommend radial tires, new spring shackles and shocks, a good anti-sway bar, new king pins, a good alignment, and good well adjusted or upgraded brakes if you want to drive at highway speeds. A double circuit master cylinder is a good idea as well as a correctly adjusted proportioning valve.
