There are also a lot of random plated parts on a GS, such as chain adjusters, various brackets, wheel spacers, etc, and having a plating kit to clean up these parts is invaluable.
The cost of the Caswell's zinc kit is not cheap, but it's a bargain in the grand scheme if you want your bike to look properly "restored". You can replicate a lot of the kit for cheap too, purchasing commercial parts (pump, heater, thermostat, bucket) instead of getting the kit. Things I strongly recommend though are the zinc brightener, yellow chromate dip, and blackener. The blue chromate is a sealer and recommended as well, although I haven't use it yet. Caswell's electrolyte chemicals would be nice to bypass due to cost. Not sure how well the home brew works though. Might be good, or not. A gamble that might set you back further $$ wise compared to just buying from Caswell's.
At any rate, I love my zinc kit and count of one of the better purchases I've made.

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