Is he a retired Dry waller??:drunk:thats what my old man was thinking. and i know that sounds pretty lame, but hey, with a '69 camaro, a few preludes, a couple of old datsuns & nissans, and a porsche under his belt, he might know something... lol.
Be sure to grind the paint off around the holes and even file the inside edges of the holes. Remember its easy to warp the metal even when plugging holes. If the holes are under 1/4" you'll be fine not using a filler piece behind.
Best of luck!