I don't care about tire sizes, I want to know how far away the rim would be from the center of the hub. Basically - would it be possible to use rim brakes on a frame designed for 26" wheels if I put 700c wheels on it? How much difference is there in the position of the braking surface?

I'm thinking about building a sort of cyclocross bike with 700c wheels based on a cross-country mountain bike frame.