When you say "your own version" of the map, what does that mean? Basically, yeah, if you have taken an existing map and re-drawn it in your own style, that's good to go (I can't even count how many people have posted their fan maps of Tolkien's Middle-Earth over the years). If it's a map drawn by someone else that you've touched up on Photoshop to alter some colours, add a few city icons, or something to that effect, then I would say it's not an original piece, if that makes any sense?