I would even go so far to say that the front wheel doesn't matter much. Framewise, geometery matters more than quality (if it fits and rides nice). Same with handlebars, seat, seatpost and stem. These are what you'll probably end up mucking around with later to dial in the fit.
Just beware that building yourself ends up costing more than you think, but it's also more satisfying than you think. Mostly you forget that you need to buy things like grease, odd little tools you didn't know existed, and other stuff that just creeps up. But, it's really fun. In fact I'm ditching my perfectly fine 2003 Bianchi Pista in favor of building up a used frame and parts I bought off Ebay. I miss the satisfaction of riding something I build and I wanted a nice old lugged steel frame.