Interesting question, Herr Krebs.
The left-rotation couple has the rotor hub at one end, and the tail rotor at the other - well above the CG. No idea where the axis would be.
The right-rotation couple has the rotor hub at one end, and the CG at the other end. I don't think the axis could be at the extremity, at the CG.
But does it really matter, other than giving you something to think about, and divert your mind from the lack of Lou Rawls and the closure of Dan Murphy's?