Good evening Steve,
I don't have specific experience with what you're trying to do, yet I did go in the other direction with my truck. Maybe browsing through that thread could give you some ideas.
How do I adapt a 61-70 steering wheel to my 72?
One difference that might interest you is that the 1972 steering shaft has an extra protrusion at the end, which might be there to prevent the '72 horn button from being pressed in too far, which could stress out the plastic. As far as I know this protrusion's kind of mysterious; nobody's certain about exactly why it's there.
Hopefully somebody will have done this exact modification and will add to this!
Robroy