Len - Kodak Portra 160 NC on a 25.4 cm x 6 ft roll is available from any Kodak dealer. 25.4cm is equivalent to 10 in. Why Kodak mixes up two different measuring systems in one description is anybody's guess. Curiously, there is no indication on the box that the film is for Cirkut cameras. The film does not seem to be listed on any of Kodak's on-line information sites. There is no minimum purchase, buy one roll, or twenty. I believe its around $35 a roll and was readily available as recently as last fall. This may not be widely known. I recently saw an expired roll of this stuff sell on the auction site for more than a fresh one would have from a dealer. The catalog number is 847 0940.
Speaking of having FUN, I would be most interested in making contact with any experienced Cirkut shooters in the Seattle area for exchanging ideas and hopefully going out on a shoot. I have an untested #10 that Ron Klein cleaned up for me. Spring is just around the corner.