My LL16D is a perfect, snug, fit in my Hiscox dread case. I found this odd because my old LL6 wouldn't fit a standard Hiscox dread case as the lower bout was too wide. My Brook parlour came with a Hiscox case with a couple of additional velvet-covered foam pads included to take up the slack. Have you tried Thomann? They usually suggest a case to fit a guitar on their website and they are a Recording King stockist. Alternatively the Hiscox site offers fairly precise dimensions for the interiors of their cases.
http://www.hiscoxcases.com/guitar-cases.htm
The bottom bout width of your 12-fret OOO is about 382mm (Martin spec), and the Hiscox OOO case will accomodate guitars up to 395mm so, in theory, it ought to fit.