I was not aware of the 1968 book, but was able to get an image of the 1962 book I referenced for comparison (Uehara sensei is on the far left). It was a little different than I remembered, but we can see that the information is the same, save that Uehara sensei's employment and (incorrect) dojo name are missing in the 1968 version. As his photo is the same, this appears to simply be a reprint done again without Uehara sensei's consent.
I do not have knowledge of every Hakko-ryu publication, but the mere existence of the 1968 volume does not change the essential facts.
First, that Uehara sensei did not attend any Hakko-ryu seminars except for the few days in 1962, as supported by Hakko-ryu publications themselves.
Second, that Uehara sensei's name and photo were used without his knowledge or consent (along with many other sensei of various ryu-ha).
Third, that the circumstances of Uehara sensei's participation in the seminar in 1962 have been corroborated by statements from other people, including the Hakko-ryu shihan in charge of his instruction.
It would be interesting to hear any information from the Hakko-ryu organization, but anything contradictory would have to address each of the points above to be credible.
Aaron Meldahl