Hi Doug
The #10 camera usually came with a 10-18-24 triple convertible lense
The length of the 360 image will be 2πr or 2π focal length, so
6.28 x 10 = 62.8” (kind of like a widelux focal length)
6.28 x 18 = 113.04”
6.28 x 24 = 150”

I have a 24” apo artar on my #10 and routinely shoot 8 foot negs
http://jamieyoungphoto.com/Cirkut%20...eople%201.html

I was also thinking of film rolls Kodak sold, labeled at 6 feet, but often 7-8 feet long.
No reason you couldn’t shoot shorter ones, but you might find that using a longer lense like the 18" group will work well for some of the shots you’re thinking of doing.

I’m tray processing all my cirkut work, and it works for me.
What are you going to do for film? Have you looked into this at all? It’s a bit of a problem now and worth looking into before you get a camera. If you find a source let me know.
Also I’m planning on going to Bill Schwab’s Photostock 2008 3rd Annual Northern Michigan Photographer's Gathering (about 90% sure) and would be happy to go out with you and show you stuff with a cirkut. Or if you are ever in Madison, WI