Since its only a flat bed, the cab would be easier to transplant since your drivetrain, brakes, etc are already complete in the 84, and parts are readily available. Given that you want to use it for a daily work truck I'd consider going that route. Your tape measure, a pencil, and some grid paper will be your best friend on this one. Your steering, radiator, inner fender wells, and cab mounts are a couple things that come to mind right away that will need attention. Take a look through my photos and a couple other builds on here to get ideas, I have seen a couple of cabs transplanted onto newer chevy C30/3500 frames
