Repairing pot metal with fiberglass, or any other synthetic agent is rather poor advice. This will not work, and is a waste of time. I would not purchase the reproduction stuff because it fits like crap on orginal fenders. Stick with the orginal pieces and try to fix them. You must grind down the affected area and either TIG weld it, or use alluminum welding rods with oxy-ace. torch. If you are unable to locate alluminum rods, or have feel they are too difficult to use, get something called "alumiweld" rods. I have used them fixing some pot metal and they are very easy to use with a oxy-ace torch. Just be sure to scrape the top layer of oxidation once you have reached the melting point of the pot metal, that way the stuff will stick. As for the missing pieces, build them up with the filler rod and grind them to shape. If you have had little or no experience with welding, locate an experienced body man.