I apologize if this sounds anal but in the very first post the questions was asked regarding the proper form for a "high block." I have been taught that I should never think of the motion as a "block." Koboichi means that "attack and defense are one.' The same movement envisioned as a block or a parry or a counter etc will have a different quality and that nuance might actually reveal the answer to your question.
Since he asked three and a half years ago, I'm guessing he's found the answer before now