You might want to have a look at how Tony (Striker) has his Orion ED80 setup, see
http://www.iceinspace.com.au/forum/s...ad.php?t=11015
I myself use a Losmandy DUP plate with 125mm Losmandy guidescope rings in a side by side setup, using the standard rings and dovetail that come with the scope don't allow you any freedom of movement, you need that to get a guidestar or, if imaging, allowing the main scope to guide and offset the smaller scope to the target.
Cheers
JohnG
EDIT: The attached picture shows my side by side setup with the William Optics ZS-80 and Losmandy Guide Rings.