Dear Mr. Haft,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located 30 series in the Records of the Indian Health Service,(Record Group 513) that reference your specific time period and may contain information on IHS policy . For guidance and access to these records, please contact the National Archives locations via email as referenced in each description.
We hope this is helpful. Best of luck with your research!
[Information provided by Cody White, Subject Matter Expert]