That should be a great freeway cruiser with that setup. What size tires are you running? I ran a 235 with a 3-speed and 3.70 gears, and 14" tires for a lot of years. No problem running 60's, 70's, and sometimes 80's if I was really pushing it! If you're running 235/15 tires, the RPM should be right in the good cruise range at highway speed.
Jerry