Thanks guys, I've been putting a lot of thought into this!
I only used basic tools,
Hacksaw (removing the canti bosses, rough cutting the brace tube)
Files (10" flat second cut, 6" and 8" round second cut)
Shop roll emery cloth (1.5" wide, 80 and 120 grit)
Mole grips (to weigh the cable stops down and help remove them when heating up the old brazed joints)
Jubilee clip and old arc welding rod (to act as a fixture to hold hose guides in place)
Oxygen and acetylene bottles with torch (I understand that you can use MAPP gas torches - DIY stores / builders merchants but I haven't tried this, I think it will depend on what melting point the brazing rod you have are and what the melting point of the braze used from the factory is if you're removing braze-on with heat).
Brazing rods
Silver solder (I used this in the bottle cage bosses in the middle of the top tube as it has a lower melting point, so the really thin bit of the tube doesn't need to get too hot).
Flux
Then there was some practice brazing with similar thickness materials, before going near the frame!