Here is a discussion of 26 x 1 1/4 wheelsets:
http://www.bikeforums.net/classic-vi...wheel-set.html
Post 3 suggests that 700c might work but the OP will have to try it out. I wouldn't go with 27 inch rims and tires.
The thread also discusses tire availability for this size wheel.
This is also useful,
26 Inch Bicycle Tires