Sorry, Bill & Ian - I can'tbe absolutely certain on this.
Hans did comparatively little in 1967, by his standards - I think he missed the TT following a small "off" at Tubbergen on May 15th.
The "Hobu" (Hans Otto BUtenuth) didn't appear as such in any other programme in 1967 (I have all his career programmes in the archive, or damn nearly all!) and only once in 1968, oddly enough at Tubbergen on June 3.
Some years ago I did ask Margot about this "Special", and as far as she could remember it was a 440 Black Bomber Honda bored to 498cc.
Don't understand the "4" in the TT programme, but can only say that if Margot says it was so, then it was so :!: