They couldn't work worse worse than they did (ie not at all) they are off one of my parts bikes and probably the dirtiest carbs I've ever seen. They had creepie crawlies, splattered paint, seized butterflies, loads of varnish and a thick layer of black oil.
I ditched the orange cam covers. You have to try these things, but like paint, what you get at the end is not always how it looks on a colour chart. Going for a brushed alloy engine now, probably with black side cases.
Powder comes in unlimited colours and many textures. Silver definitely - some very convincing chromes and some gorgeous translucents. Take a look at prismaticpowders.com