Wheel and tire suggestions for an early '80s D150

If you think 15s look small, you may want to look for 17 inch wheels.
There’s tons of different styles, anything that fits on a 4.5 Mopar pattern, or Mustang wheels would work. Almost all 5 lug Mazda wheels are also 4.5. There’s so many different wheels in that size it just depends on what type you’re looking for.