Measured the granny I mounted on the Nervar big ring. It came out as an 86BCD, which is no longer made. I guess I need to now go on a search.

Here's a closeup of the mounting hardware and you can seen how nicely spaced the bolt holes came out. I'm guessing a 74BCD could be mounted, but it would push the holes close to the inner mounting holes. BTW, those inner bolts are the ones Velo Orange sells. While not looking anything like the original, hex bolts, they certainly are superior and easier to tighten.