I have a '51 one-ton with a 9 foot box and I was told it came from a chicken farm. This may be where the guy I bought it from, I don't doubt it.
However, when sanding off the old coats of paint I found the doors painted with the name of a local rock quarry. No wonder the sides were beat up so bad.
I had the bed wood made by a local Amish carpenter from some drawings I did and while he was at it I had him make up some stakes and sideboards. The bottom sideboard runs the full length, the second runs two-thirds and the top sideboard just beyond to the first stake. It looks good and seems to make the cab appear shorter and better matched to the cab.
Unless you are going to use your truck to haul hay or whatever, I'd say keep the 9 foot bed. I thought about a flat bed at first and an glad I kept the stepside.