There are songs that someone makes so much their own that they seem to own them, even if they are a hundred years old. Dave did that with several songs, for me. Duncan and Brady was another one I never even tried to do. I don't think that Dave took Bob Gibson's "arrangment" of Tell Old Bill because their styles are so different. You can take the words and melody and not change a thing and still have a completely different arrangement of the song. Who knows now? Dave may have heard Bob Gibson's album as it had been out a few years before Dave released his first album and was on a major label.
Jerry