I agree, clean it out the best you can and then put it back in. Put a good filter before the fuel pump and after and it should be fine until you can get a new tank or have it recoated professionaly.
I would follow a bit of everyones advice, try flushing the tank out with water (with nuts and bolts or peagravel) to remove the stubborn deposits and then use compressed air as stated by speed6351 to blow all the loose deposits and dust out, then either put it back in the truck and fill it with fuel or coat the inside with wd-40 or the like so it doesn't rust while its sitting waiting to go in the truck. Id still run a good filter before and after the fuel pump just to make sure.
