Dont take any facts from this story for granted and/or exactly true. It's a story and most of the facts cannot be verified.
But you have pointed out a nice fact, that can possibly be verified. I think that it's a great idea to put this story back in it's time context. They didn't have computers back in the days so any cryptography would be a pain in the ass to do. A cryptographic tool like this wheel whould be an easy way to do the job.
The problem is that the wheel contains letter of the alphabets and not number. In the first cypher page, the greatest number is 2906, witch cannot come from that wheel alone...
Thank you for that fact,
Here is a link i have found if someone else is interested: