14mpg would be almost double what its getting now. Its gets 9 on highway and 8 just running around.
I know your's is a 3/4 ton but, are you running the stock motor?
I had a 78 F-150 with a 351M/4-speed trans and a 79 Bronco with a 351M/C6 auto and it was a tale of 2 motors. The 79 was stock except dual exhaust. It was plenty fun for a 16-17 year old kid. But, It got about the same gas mileage as you're getting.
My 78 which I did an amature resto on, was a different tale. It had mild cam of unknown specs, (stock valvetrain) otherwise, stock distributer, new plugs, wires, filters, an edelbrock 4bbl carb and intake, headers, and dual exhaust with no name glass packs. After that it got a legit 14mpg.
