Overall overlap, or lobe center understanding?? ¿.

My thumpr cam has 74 degrees of overlap and works fine in my 10:1 318 with 3.23 gears out back as a street car.

Yes, gas mileage is bad.

To me overlap is just a result of a desired lobe duration and lobe separation.

because of this you can easily have two cams with the same overlap which are completely different

IMO overlap specs should often be a good indicator of how an engine might idle.