I used Evaporust as I've always had luck with de-rusting parts. But the cylinders were really too far gone. I did reinstall them, but can't be locked. The other one can, but I had better not put a different key in there, or I'm screwed.Have you tried a product called "KROIL" (creeping oil)? We have used it with some success.
Like your attention to detail! Car will be awesome when "done".
Thanks for the props!