Better check the wheel base on that Cab and Chasis 1 ton. I think you'll find it's about 3" longer than the long bed GM pick ups. I saw a guy who put a pick up bed on a C&C and the gap between the bed and cab was about 4" when the rear wheels were centered in the wheel openings of the bed.
Also, if it's got the cab and chasis 14 bolt dually rear end, the inner wheels won't clear the inner wheel well of the bed (both single rear wheel and dually pick up beds).
Check out the wheel base first, I'm pretty sure if it was a cab and chasis model from the factory (not a previous owner pulling off the bed and building a flat bed for it), it's going to differ from your 1/2 ton.
Eric M.