I am not sure of the distances, but you could try a special fiber jumper and Lx cards. We were told that we "Might" need this for our connection between two buildings over MMF. We are using LX Gbics. After testing, we found that it worked either way, so we left the special jumpers in. The jumper is called any number of things. I might combine the names, but it was along the lines of a mode conditioning offset launch cable. It makes the multi-mode cable act more like single mode. I'm sorry I don't have more info, but this might point you in the right direction.
