Nessism is perfectly correct, you will need to zink plate and cromate the steel hardware. But you also need to be able to secure the screws so they dont end up in the cylinders.
therefor my comment about drilling them so that you can flatten out the ends.
For what it's worth...Wired George media blasts the carbs he rebuilds and then sprays them with some clear coat junk. I've rebuilt a few sets that he previously rebuilt, after the owner couldn't get them to run right. I found blast grit all through the inside of the carbs. The blasted parts were starting to rust too. Not a fan.