A Raven with 700c wheels would probably be perfect. (or even 650B... just saying)
Hi Steve!
If 650b would do...you could like do-it-yourself and lace on a pair. See: http://www.thorncycles.co.uk/forums/index.php?topic=3893.0
I found the brake boss placement on both my Sherpa Mk2 and Nomad Mk2 would allow pads to nicely meet-up with 650B wheels, and overall diameter with 650x38b tires is within 1mm of my 26x2.0in Schwalbe Duremes. In other words, the rims are larger, but the tires are smaller, so the outside diameter is essentially the same and the brake pads would reach fine on my two examples.
But, except for the aesthetics of seeing larger wheels, you'd end up in the same place except for running narrower tires at the same diameter. However, checking my clearances carefully, I *think* you could safely go to 650x42B Grand Bois Hetres and still run mudguards and have stay clearances, but I can't guarantee it; you'd be wise to check the frame you intend to use.
That said, you'd probably be better off with a true balloon-bike 26in tire application instead, but that gets you back to the aesthetics of smaller-diameter wheels.
Cycling shouldn't be this difficult....
Oh, it's the challenge, Steve; where would we be if it was all easy?
Best,
Dan.