I don't remember a biography but it seems like he was on record at some point (King Encyclopedia, early 90s, I believe) saying he wanted to write a book about Elvis. Another on baseball and another on Christ, I think. The book about Jesus was supposed to be a black Jesus or something. Am I dreaming this?
Anyway, assuming he meant fiction he has met his expectations, in a way.
No Elvis book, but Revival probably comes close to that Johnny Guitar/rock and roll mystique. The Green Mile touches on the Christ figure book and the baseball book could be Blockade Billy or Faithful.