you can download any mountain you want from http://terrain.party/
the thing is that you will get the height map, so you will need a way to convert a height map to mesh, after that do some retopo, make UV-s (Planar)) and find the appropriate satellite images for your new mountain, delete the unwanted objects from texture (eg. roads , buildings, cars etc.)
Edit: this cool thing will help you find your perfect mountain , it has 3d camera, 3d landscapes, loads fast and looks pretty https://earth.google.com/web/