Hi thsc42,
I’m also interested in producing some historical maps based on OSM, i’ve seen a few examples (http://chnm2010.thatcamp.org/05/20/openstreetmap-for-mapping-of-historical-sites/) and other threads dealing with that but nothing advanced.
I have a lot of subjects about historical stuff that could be put in OSM, and i’m interested in the different ways to make movements and changes in time visible for some places or items : evolution of some borders, description of an entire military campaign, street changes in city, ancient monuments localization etc. ; a lot of things, as you can see 
Regards,
Zatoune