I'll be interested to see what this thread turns up. On both occasions I've gone looking for rings for a 10" OTA I've ended up with Parallax rings. I tried to get some from Peter Tan in Hong Kong but he never returns emails in my experience.
http://www.tan14.com/Others.htm
The Parallax rings are quite heavy (1.6kg each) compared to traditional rings that come with a 10" Newt so you'll probably be looking at an extra counterweight.