Sanding

you could sandblast the truck, and start the bodywork process over, it could get costly and take more time, but if you want it done "right"...

If you want to strip the truck down to bare metal, use a da with 80 grit on it. its gonna take some time, but it will come out nice, and not leave any gouges in the metal. if you dont want to take it down to bare metal, i would just block it real good with a long block with 80 grit on it, then switch to 150 grit to get the 80 grit scratches out. Do your necessary bodywork to it. after your done with that, spray 4 good coats for primer

Thanks for the info