Check out this old thread. You can download pdf or autocad files of a tracing of a 1937 0-18 14-fret. The links are still active. If you don't have cad software, you can print out the pdf on letter size sheets to tape together for a full size pattern. I don't have any of the bracing info.
link
You might also look on the Unofficial Martin Guitar Forum, http://www.umgf.com and stickied to the top of the Technical section is a discussion where folks have posted pics of their Martins with a light on the inside so you can see the outline of the braces. I think there were some 0-size 14-fretters in there. Not exact, but should give you an idea.