Going from (fading) memory here... With my 4.10s, 275/60R15s (loaded radius is actually shorter than advertised 28"-ish diameter, more like 27.5"), loose converter... 60 MPH is about 3000 and 65 MPH is closer to 3500. I'll drive it steadily at 65, but not any faster for any extended distances. The noise factor above that gets on my nerves.

Not sure what exactly you'd do to build it to live longer at a projected cruising RPM, vs how it should be built to handle the peak RPM. My junk is built for a performance goal: the cruise RPM on the highway is a byproduct of the package of compromises I've made to achieve that performance goal.