Thanks for the many great ideas, I'm searching around and keeping my eyes peeled. 240mm g-claron sounds very good. I am a little worried that 210 won't be telephoto enough for my purposes; my girlfriend has a Ilex-Caltar 210mm on her monorail and while it is certainly a step up I wouldn't mind a little more reach. That being said, I'd love to be able to close the camera with the lens mounted, but that may be a pipe dream.
Does anyone have any thoughts on the Wollensak tele-raptar 10" 5.6? It looks like it will fit and I've seen scattered positive things said about it, but limited serious discussion.