Wow, I should go away for a week more often.
Thanx for the replies guys.
Spindizzy, if I could ask a couple of questions.
The tail area of your V-tail, is it equal to the area of your hstab, vstab?
What is the rotor dia of your coax? and disk loading?

All of my calcs have been based on coax helo formulas, so bringing them across to gyros has been an interesting experience.
I have a paper done by NACA on the best spacing for the rotors, which is 10%R. This seems to be the best mix between drag of the second rotor, and losses from the other rotor.