I'm old and forgetful so correct me if I'm wrong but I think MS 67 didn't exist in the original ANA standards, only MS60, 63, 65 and 70... and needed to be accompanied with the coin's detailed description of the flaws as to why it's not perfect... which is sadly missing in the TPG's system. I feel the TPG's mid-Gem to Perfect numbers were only a marketing ploy... and subjectively debatable.
The First Edition of the ANA Grading Standards only recognized 60, 65 and 70 as MS-grades, but before I opened the ANACS grading service on March 1, 1979 I recognized the need for additional grades, so I added MS-63 and MS-67 after consultation with various relevant people.
I was thinking he meant the GSA dollars/holders that you could submit and have graded in-slab, to maintain the original holders.