Jeremy,
There are probably a number of different copy lenses by different mfg that are in the focal length that you want. The ones that seem to be used a lot by photographers are the 305 and 355 G Clarons. I doubt that you will find a barrel mounted 355 since Schneider discontinued the G Claron line and that lens will cover 12X20 format.

I personally have bought a used 305 RepoClaron and have been pleased with it. Schneider told me that the RepoClaron has optical performance very near the G Claron with less coverage. I have never run out of coverage with mine. Mine was mounted in a Compur shutter when I bought it. You may be able to buy a used lens like this already mounted in a shutter for less money then buying a barrel mounted lens and later having it mounted in a new shutter.

I have seen the Repo Clarons come up on Ebay occasionally. Good luck.