'67 Mustang steering upgrade

Hello. I have a '67 Mustang with the long steering shaft gear box (power steering). I'm needing to replace it and decided to switch over to a collapsible column from a '68. I'm trying to decide which way to go with it on a very limited budget, but I'm wondering about the pitman arm. What I currently have is a 1", but I'm guessing it would be best to have a 1 1/8" instead. How difficult would it be to switch over, or would it be as simple as just getting a different pitman arm? Not sure if I would have to change other components to make it work. I'm wanting to know what I would be up against before buying another steering box so I know which way to go with it.

Thank you.