Just wanted to say real quick, it's not hard to patch gully dwarves in the broad sense, imo. Instead of making it a discrete subrace, it's just a somewhat rude slang term like "hillbilly" for dwarves who ended up in rustic hardscrabble settlements. Broadly speaking they're not going to have the polish and more cosmopolitan knowledge pool groups who didn't have to do back breaking labor every day to scratch out a subsistence lifestyle without much outside contact will have been able to acquire, but all basic faculties are comparable, just a matter of what opportunities have been allowed by the environment.