Just found a whole bio about him in "The History of Tulsa, Oklahoma, Volume 3" by Clarence B. Douglas, 1921 (available free to read on archive books). It reads;
CHAUNCEY M. GILLESPIE, M. D.
Tulsa has a long list of capable physicians, men whose thorough training well qualified them for the active and responsible duties of the profession and in this connection Chauncey M. Gillespie is well known, becoming a resident of Tulsa in 1918. He was born in Belfast, Ireland, May 4, 1879, his parents being Robert and Katherine (Watters) Gillespie, both of whom were natives of the beautiful
Emerald isle, where the father was a missionary of the Presbyterian church. He went abroad in missionary work, spending thirty-five years in India. Both he and his wife have passed away, leaving a family of eight children.
Dr. Gillespie of this review pursued his education in a boarding school of London, England, and later in the University of Edinburgh. Coming to the United States in 1904, and wishing to enter upon a professional career he finished at Loyola University of Chicago and won his M. D. degree in 1910, having devoted four years to medical studies. Since February, 1918, he has resided in Tulsa, where he has gained a large general practice.
On July 4, 1910, Dr. Gillespie was married to Miss Alexis F. Bisen of Whiting, Indiana. They are members of the Holy Family Roman Catholic church. Dr. Gillespie is identified with the Knights of Columbus. He was secretary of the board of health at Whiting, Indiana, when America entered the World war and volunteered for service but was not accepted. He belongs to the Tulsa County, Oklahoma State and American Medical Associations.