MP, that is a Gen 4.0 holder used from 1998-2002. My understanding is that the 65's and 66's were graded EARLIER, from 1996-97....and in the Gen 3.1 1995-98 holders which are considered OGH. Now, the coin could have been cracked out and re-holdered later...not sure if collectors were doing that 30 years ago.
Exact information is hard to find, but i believe if not mistaken someone posted a 64 but according to the info you provided this wasent possible, if i can, will try and do the research and try and find the thread but i know it wasent a 65 or higher, will see
I believe it was WF 1908, just like the one I was looking for actually liked the 66 in the OGH but it sold before I could pull the trigger.
There is some interesting info in this thread on the CU forum (started in 2015 when gold was at $1160) https://forums.collectors.com/discussion/942201/well-fargo-st-gaudens-vs-non-wells-fargo#latest
Better information in Roger Burdette's Saint-Gaudens Double Eagle book. Very informative on what the specific problem is/was with the 1908 No Mottos....not so much strike as die characteristics and flaws. I'll post more direct from the book when I get a chance.