BB 440 Mileage?

i am interested to see any responses. years ago I had a 4x4 Ford Ranger that I put a hot rodded 302/c4 in it. 4:10 gears with 31" tires, it was a pig. I leaned it out as far as I could and if I kept the tach at 2400 rpm or so it would get 14 or so. Drive it at normal speeds on the freeway, 8 was about as good as it would get.