Flare nut wrenches are made to make full contact on 5 of the flare nuts 6 sides, allowing to work more like a socket or box end wrench. You should be able to get a good set from the auto parts store or local Sears for a reasonable price. Redoing the lines isn't too hard, you'll need to measure the lines to get the overall length and you'll also need a good double flaring tool. If you've never done double flares before, you might want to get some extra line to practice on. Here's a
video I made a while back showing the process.
MAster cylinder diagram.
