Just found your posting.I have a John Newton Watkins in my data base. He married Mary Coyle in 1871. He died in Harrison Co in 1925 and is buried in Longview Cemetery. I have no birth but he would fit your John.
I have no way of knowing if he is the one you are looking for as I have no interest in the Watkins family except as it relates to Mary Ann Coyle. She is a collateral relative. If this helps you a bit, I'm glad I could offer the suggestion.