With my 1275, and a 3.9 rear gear, I run about 3600 RPM indicated at 60 MPH. It goes up about 500 RPM for every 10 MPH, so you would be looking at somewhere near 4350 RPM at 75. That's with 15580SR13 Michelins on it. I'm putting 175 70 Sumitomo's on it this weekend, and I'll see what it does then.
With the 3.9, acceleration is acceptable, but I still may drop a 4.55 in, as I never go on the freeway with it anyway.
The 3.7 was in the 1500 cars because they don't rev as high as the 1275 will. And, they are real dogs by comparison. (Don't all you 1500 guys beat me up for saying that! /ubbthreads/images/graemlins/nonono.gif)
Jeff