The rims would need are 8 lug on 6.5" circle pattern. They are VERY common. Ford used them up to 1999. Chevy used them up to 2011, and Dodge is still using this lug pattern.
I have 16" rims on my 48 3600 stakebed. depending on what rims you find/like, you can find tires of various heights to get the look/fit/speed you are looking for.
I looked for new and repop "short" running boards and had no luck finding any.
Jon
