i changed out the wheels on my old Peugeot, also 27" to 700c. the original calipers could accomodate it, but they sucked to begin with. i ended up getting Nashbar's long-reach calipers. $30, they work a lot better. i know some people scoff at Nashbar products, but hey, it gets the job done, and inexpensively.

http://www.nashbar.com/profile.cfm?c...0Road%20Brakes