Neither the 1964 or 1981 games against the Barbarians are included in the official Māori games played that year (based on what is listed in The Encyclopedia of New Zealand Rugby). In 1981, for example, the Māori only played Counties and then South Africa.
The 1964 match is not a first-class fixture because it was played on a Sunday. Matches in NZ played on a Sunday did not qualify for first-class status until 1970.
The 1982 Rugby Almanack refers to the 1981 match as a Maori Invitation XV v NZ Barbarians. It was NOT NZ Maori v NZ Barbarians but is a first-class fixture.