With disc brakes it will probably work. My fixed gear conversion, which started life as a 26" wheel mountain bike, now has 700c wheels. In my case a standard road caliper brake was perfect to reach from the fork crown to the brakeing surface.

Here's a word of warning: You can almost never change just one part on a bicycle. Everything works together so, when you change one part, you almost always have to change something else to get the whole package to work. If I already own parts, I'll generally trial fit them to see if I can make the combination work. If I'm buying parts, I'll hold out for stuff that matches.

Good luck.