Looks like OJS will simply be taking the donated code for NLM handling, rather than writing their own, and the donated code uses NLM 2.3, so I'm now writing a converter to turn my 3.0 output into 2.3. There are about four major areas of difference, two of which I've already dealt with, and I've also gone back and elaborated one area of the original TEI-to-NLM-3.0 conversion for greater consistency.