Dear Mr. Womble,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog but were unable to locate files of John W. Fritz or correspondence of the Deputy Assistant Secretary in the Records of the Office of the Secretary of the Interior (Record Group 48) or the Records of the Bureau of Indian Affairs (Record Group 75) during the 1970s or 1980s.
We searched the website of the Choctaw National and located a copy of the 1983 Constitution.
We hope this is helpful. Best of luck with your research!