As long as you are tearing the house down to the foundation, it may be a good idea to prepare the basement for the next 100 year flood that seems to be happening every 5 years. That would be a good time to bust up the floors and install a french drain and a sump pump. As you start to build your train room think about keeping things elevated with some high-end shelves. Make sure that anything on the floor will not get ruined by water.
And don't forget to post pictures while the room progresses.
