I regularly drive between 1600 and 2000 RPM now. Used to be hard to maintain anything under 1800 in 5th gear before (I have a tremec with .64 5th gear and 3.55 gears), but now I have a properly curved distributor, lots of initial advance [24°], and absolutely no knocking in the driveline down to almost idle (I can coast to 1200 and slowly ramp up again). Before this distributor, I could not maintain 90 km/h (56mph, the posted limit on backroads here) in 5th, I had to stay in 4th.

Of course, my car is much lighter, around 3000 pounds.

I drive to and from racetracks, usually between 2000 and 2500 RPM, at which point I'm slightly above the highway speed limit. I get 14 to 16 mpg.