would you really want it brazed and not TIGedI was planning on doing that too but I happened to pick up a springer with twisted front leg. Anyway like Unkl Ian said mild steel is the way to go. If you are using a stock type springer front leg get some 3/4" bar stock and watch some video's on youtube how to twist bar stock then bring em to a machine shop and have the ends turned down buy some repop early front leg springer lugs and have it all brazed together. Don't forget to pin the top and bottom before brazing.
All early springers and frames were brazed. There was no such thing as tig welding. The lugs that diligas is referring to slip over the the ends of the turned down legs and the braze just holds the caps to the legs. The early frames were made the same way, everything kind of fits together like a lego set and the brazed joints just keep things from slipping apart. The problem with tig welding things like this is that a tig weld is much hotter than brazing and this hardens the metal. On something like a springer or frame, you want mild steel and not heat treated steel. mild steel will flex and bend out of place if the forces on it are too great, but hardened steel will crack and just break. brazing can also be used to join dissimilar metals. early parts such as the springer lugs and the joints that held the pieces of frame tubing together were cast. welding cast iron leads to cracks along the welds. hence, you can braze a cast piece to mild steel and it will last a lifetime if done properly. I'm not a metal expert, but this is the way I was taught to understand the whole brazing thing. hope this makes some kind of sense. BTW, most new springers are made from all mild steel, and are mig or tig welded, but were designed to be welded and not brazed.would you really want it brazed and not TIGed