definitely buy a new pump. it will come with a gasket. make sure all your fillers are there, as mentioned. it couldn't hurt to throw a new thermostat at it. and fill it with a 70/30 mix of water/antifreeze. water cools better than the green stuff. and do a flush before you do your final fill. if one of your pump baffles corroded away, who knows what else might be floating around in there.
added note-distilled water is less corrosive than tap.