Did you ever get a reply to this? I'm similarly trying to fix up a map and put the mountains exactly where I want them. I've yet to decide which type of map I want to do in the end, so I'm playing around with a parchment type drawn map vs a map similar to what you show in your first post here. One of the better ways to achieve what we're thinking of seems to be Rob A.'s tutorial "Simple Mountains in GIMP". That will work with the kind of map you show above, but I'm not sure about the "hand drawn parchment type map". There's a tutorial for that as well, but I seem to have lost it. I think it was something like "Simple Fantasy Map" or something very similarly worded. Worth checking out these two tutorials, I think.