There is 20x24 polaroid film and I have even seen 40x80 polaroids (from a camera the size of a room). I have never heard of R14 lifts.
http://www.polaroid.com/studio/20x24/ if your close to New York, Boston, Cambridge, Prague or San Fransico.
Hate to say it, but why not drum scan your final image and print it at whatever size you want.
Originally Posted by Agency mh