There are some really high quality clear powdercoats available that can be applied over polished aluminum and triple plate show chrome. Find a coater that is familiar with this stuff.
There used to be clears that looked yellowish and that stuff is no good. You might have to research for powdercoaters that do motorcycle custom work.
Better chrome plate shops that do Harley, hot rod, and antique car parts might know people that can do the clears.
Parts may have to be degreased and baked many times until the oils stop coming out of the pores of castings. The finish and results of your work can last a long time if you prepare your parts correctly. Hopefully they will clean up pretty easy and the clear powdercoats preserve your work.
Some people don't like powdercoating, but the powders have come a long way in the last 15 years. Around here near the ocean we used a polyester recipe powder which had a high salt tolerance. I had a air filter cover on a Sportster that I had stripped then copper plated. My friend's shop put a clear over the copper and it looked good 10 years later when I sold the bike.
Meanwhile I restore vintage Mercury outboard motors. I blast parts with glass bead at 60 PSI and get a nice no etch finish. Although I paint mine with PPG paint, I know guys that put clearcoat PPG over the aluminum with great results. Talk to an automotive paint store about clearcoats. Good luck, DaytonaJohn
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