..on which everything was silicon bronze, I had the proper width of the chain plates sheared out of flat sheet stock at Alaska Copper and Brass in Portland OR. That was 1979 and the only way I could do it back then. Sounds like it has not changed. I'd have to say that making everything on that boat out of bronze was a great choice that I never regretted. But.....if you're having it done at a yard I'd think about 316 SS and/or the L as Roverhi suggests. They're not gonna know bronze, you'd have to line up all the parts to make it work, etc., making way bigger of a job out of it than you might like to do.