Thanks to everyone for their replies, much appreciated. I think I know what the score is.
I do have a K3. It has F type carbs fitted by persons unknown.
The forks internals are the same as the F type, contrary to the Haynes and Clymer workshop manuals. However, a later version of the parts list for the K3 shows the same fork internals as mine. I therefore think that Honda changed the K3 fork design to the same as the F type after July 1977 (the issue date of the manuals I have).
I think this explains it and I'm happy to believe this.
The forks are the same externally by the way, the earlier K3 design has a central rod through the centre of the spring, the F type does not.
Nurse Julie, mongrel Millie looks very nice and I bet barks very loud as well.
Thanks to all
Mariner Wayne