The '54 3100 beds are the same length and width as the earlier ones, but the depth is about 3.5" more (at the tailgate). The '54 eliminated the mounting bolt spacer blocks, so that the platform height was lower (allowed by the lower frame kick-up), and the overall height from ground to the bed rail tops was slightly lower. Putting the '54 bed on the earlier frame will require the spacer blocks to clear the frame kick-up. The platform height would be the same as the '50, but the height to the bed rail tops would be increased by about 1.25".
It should work. I'm not sure if the mounting bolt holes will line up exactly the same. If not, it wouldn't be hard to drill some new holes.
