Hi Gary
I originally used guidescope rings but changed to the Casady Tandem Guidescope Aiming Device (TGAD) look here:
http://www.robincasady.com/Astro/TGAD.html
To get the finderscope on the ED80 so I could get at it, I rotated the tube 90 degrees, the finder is now on the right, I need it there to get at guidestars using the TGAD, also my crosshairs are aligned so when I centre the guidescope, the target sits in the centre of the ST-4 guider chip.
Cheers
JohnG