Our "medium soldered cable" (#40-220) is similar to what he is looking for.
It has 12 links per inch, is available by the foot, and comes in white plate, yellow plate, and copper plate.I think that the links are a bit more oval than traditional "Mission chain." I think that Mission chain may have rounder, more "O" shaped links.
This makes the Mission chain look larger than the medium cable chain, since each link is wider.
We do have a very pretty (but basic) "drawn cable" chain in 12kt GF, but it only has 6 links to the inch. It has nearly rectangular links. It is also by the foot, and is #40-693.
The stock numbers above are links to these items in our online store.
I will also check on possible special orders of a round-link cable in GF and/or Gold plate, since I think the round-link cable is sometimes called Mission chain.