What is the size difference between a 27" and a 700c wheel? I've been working up a classic (probably... 1976 or so) Nishiki International to replace my too-small-for-me Bianchi frame on my fixed-gear bike, but I think the Nishiki was designed for 27" wheels and my fixed-gear wheels are 700c. Are there problems running 700c wheels on a frame designed for 27" wheels? Or are they sized closely enough to be problem-free?

Thanks!