b) 'The Gully's finish is what you have marked as the 'Devil's Backbone' finish, the marked finish was a slightly spicier solo variation. It had two starts, the traditional one marked until the ground washed out, and the more commonly used marked start to Camel's Back and traverse left into The Gully. Also, The Gully typically went left in the 'gully' up to the seventh dash you have marked for 'Devil's Backbone' then walking up the Devil's Backbone dashes.
c) Devil's backbone was never a route, just a way to join The Gully when soloing the start of Makanda Layback.
d) The marked Makanda Layback line appear to drift too far right after the slot if I recall correctly (which I might not forty years later).”