I've looked into this as well. I guess there's a reason that those beautiful Linhof Cine-Rollex backs are so cheap these days. I don't think there are any color reversal films available in 70mm--just aerial films and color neg for portraits. Check bhphoto.com, and you should find most of what's out there. If you wanted B&W reversal, you could consult with dr5.com and find a film that's available and that they can run.