Thanks for your comment. You are not alone with what you believe. Bill Wilson is my 2nd great uncle.
There are several problems with the Josey Wales was Bill Wilson story. I've addressed these problems in previous comments I have made in this thread and other message boards. The biggest problem with the "Mr. Wilson" ending is the name was a script change. Strangely, everyone who quotes the "Mr. Wilson" ending never mentions the actual book the movie is based on. If there is a final authority, you need to go to the primary source, in this case, "Gone to Texas" by Forrest Carter. The movie does a good job of following the story and at the end, it is not "Mr. Wilson" that is mentioned but Josey is called "Mr. Wells". Bill Wilson or Mr. Wilson is not mentioned in the book at all. I believe that the reason the name was changed was a logistical need. On paper, the name Mr. Wells is easily recognized as being different from Mr. Wales but in a movie where the lines are delivered on camera, the two names are almost indistinguishable. No doubt, at the end of the movie, the moment in the bar was crucial for Josey to be released from federal pursuit and the "Mr. Wells" had to be changed to something that sounded familiar to "Wales" but the audience needed to definitely hear the change. Wilson is a common name and choosing it had a good ring to it for the movie.
Several academics and writers have made this basic error in their research, trusting the movie and not "cracking open the book".
I would love to believe that Bill Wilson was the original character model for Josey Wales but there is no proof that has surfaced connecting Forrest Carter to Bill Wilson or the "Bushwhacker" book by George Clinton Arthur.
If anyone has any information contrary to what I have written, please make comment. Maybe there is a letter written by Forrest Carter that discusses who Josey Wales is modeled after specifically.