If you get your GPS out you will find that you are really doing 75 at 3,000RPM, but even apart from that, if you are eating up a lot of Interstate then it would be great to drop those revs down to 2,200 or 2,400RPM. It would be less tiring, less wear on the engine, and give better fuel economy.
If you think about it, the T'bird, and even HDs with a 6 speed box, are doing the same revs at that speed - but they have only two bangs compared with our three. Therefore the RIII should be able to do those speeds at 2,000RPM! However, I would be happy at 2,200 or 2,400.