You could make the mistake that I did - get 27" wheels built up before realising it was probably built for sprints
Still, I think it looks good anyway - shame the only brakes I can find with a shallow enough drop and nut fitting are useless Campag jobs which would definitely incur brown trousers if ridden in the wet.
The difference in size is so small I doubt you'd notice. I think it's about a 10mm difference in diameter overall, based on the amount I had to move the brake block down when I tried my 700c's on my old Viscount.