I'd use small dia flux coated brazing rod- the cleaner you can get the two mating surfaces, the better- neutral flame and ONLY oxy-acetylene (no MAPP or Propane) and I would "pin the broken halves" on a fixture to insure proper alignment and minimum of post-braze grind- everytime you grind a welded joint, you weaken it somewhat. However, I also agree with those who felt you could machine a new part from mild steel faster if you have the proper tooling- drill press, milling cutters, grinders-whatever.
