It looks so "un-Sony", but I guess that comes from having never seen a Sony set that wasn't a Trinitron, or anything Sony that was tubed.
There has been a small update to the original post at the original link (unless I missed it the first time, I was having issues getting google translate to load the entire page). It appears a lot of information and possible even a schematic for the related 19C-70 model was published in a special 1967 edition of a Japanese electronics magazine: 電波科学 1967-1
I found this link for an auction selling the magazine:
http://page9.auctions.yahoo.co.jp/jp/auction/k149449266
Though getting things from Yahoo auctions Japan from outside of Japan tends to be difficult and expensive.