Yes! But it's a process. It would be a matter of exporting and then importing the textures from the normal map variants into the ultimate variants. But with that being said, ultimate mode has a bit more than just texture changes, they also usually include lighting/fog changes and different object textures that are shared between normal and ultimate (for example; changing the big stones texture that you find in Caves 1 used to block paths are shared between normal and ultimate mode, so changing it's texture affects both modes).