Build Yer Own !
Cool !
Careful attention to detail and good solid welding will result in a nice bed for your truck , this was common back in the day when you could $ave a goodly bit of $ by ordering a cab & chassis and building your own bed to your needs...
Sadly , they all seem gone now , I remember lots of really interesting one off beds when I were a laddie .
All worked to death then scrapped is my guess .
Don't forget to weld on some rope hooks along the side , under the edges so you can tarp down loads or tie down big stuff you need to haul like Motos and refridgerators , console TV's and so on...