This place sells a lot of repro 32 ford pu bed parts. http://www.mackhils.com/mack_products/ You can probably look at their scale drawings to get a lot of ideas. Off the top of my head, I think if you measure side to side between the two vertical sidewalls of the bed on the inside of the bed, the distance is 46". A lot of guys shorten the stock bed. I think I shortened mine something like 17", which I took out of the back part so that the rear wheel looked sort of centered in the side of the bed.
I found some info there,but still need to know how high the sides/front/tailgate is,how far in from the edges are the beads rolled?how big are the beads?etc.