If the clear coat is mostly gone, that's great. Just use either steel wool or 400-800 grit sandpaper to cut through corrosion, then polish. You can even use 200-300 grit paper to remove deeper scratches and then work your way back up to 600-800 grit paper. Follow with "0000" (superfine) steel wool and aluminum polish, like "Mothers" metal polish.
You'll be amazed at those results. If you've got a good, fairly high-speed drill, or an air-powered die grinder, you can go a step further in the polishing and make it look like chrome.