According to my sister who was in the Army and served as the secretary to one of the top officers at Fort Hood in the mid 1970's, the typist's initials were required to be on everything they typed. She believes the same would have been true for the National Guard. I looked at some copies of the memos online and didn't see any initials for a typist. Have the memos been checked for this?
If the typist initials were on the memos then he or she could be identified from the TANG records. If there are no typist initials on the memos then checking on whether this policy was followed by the TANG in the early 1970's could indicate whether or not the documents could have originated from the TANG office.
Very good point.