You might be disappointed with the results. Plastic is non conductive so only method to chrome a plastic part is to vacuum plate it. Vacuum plating is not triple chrome (copper-nickel-chrome) but rather a thin layer of chroninum nitrate appled with a negative atmosphere method that imparts a very thin and not too durable layer to the substrate. Your big drawback besides durability is the headstock covers are textured and that will make the vacuum chrome even less likely to adhere to the mottled surface. If you ever built model cars, the chrome plating on the plastic parts is the vaccum process. If you remember, you can scrape it off with your fingernail and you'll have the same thing on the plastic headstock covers. I'm not trying to put a pin in your balloon, just dont have high hopes. It may look just fine but it won't last very long.