Nice find Im also A limey and American, Everybody hates me I would kill for some twiglets I know nothing about the stearing gear in the 715s, but I know that A GM saginaw steering gear from the later 70s gms with the 76 embossed were the ones to get, there (IIRC) 3 turns lock to lock, the later were allitle more lock to lock, but still good units. I drilled and tapped A gear for hydraulic assist. I used an 8" ram for the assist, but I can turn A set of 42s lock to lock at just above idle on concrete This setup is on my other rig, but it uses the setup from the same saginaw setup as yours