Great update Jay!
Since publishing the book there have been some interesting finds including the Weiss 2019 auction:
https://weissauctions.com/past-auction/n173/
Three new examples of McPhee moved him down the list but still extremely difficult (one museum copy, 3 private), others have had two new discoveries such as Hanlon but likewise remains very tough. Top half of this list is impossible to quite tough. Bottom half is possible to collect given a little patience and money.
I do hope a Griffith eventually surfaces such that we have large format examples of all HOFers.
If you have a cabinet from top half of this list we would welcome you chiming in with a picture in case we need to alter our recorded populations.