I'd base my rear gearing on highway rpm and gas mileage and get my CAM profile to match my highway cruising rpm.
My old cam profile didn't like much rpm below 2500-2800 or so, which was a real pain in the butt around town. I'd run 3rd or even 2nd gear a lot. I changed the profile to a lower rpm range (more torque) and am much happier with it over all. I wasn't looking for 'better mpg' but sure was surprised when it went up, a LOT!