From Velonomad to Nessism to the the good Doctor Deltron (and many in beween) this forum has been a big help to me building my first frame.
I used a mapp gas torch with 56% silver solder wire and 56 & 65 Silver paste (it's a jewelers thing (;-)) and even some brass to filet braze the fastback stays.
I was fearful of not having enough heat for the bottom bracket so I used a hand held propane torch to supplement my mapp gas. The joints came out fine, with nice internal filets and just a bit of silver pooling on the underneath of the chainstays.
I used 56% silver solder paste squeezed into the seatlug joints and then fed in a little 56 as it came up to temp. I couldn't have been happier with the result:
I always liked fastback stays. Nessism advised me against a socketed seat stay lug so I broke out the brass and filet brazed the stays in place. The miters for the stays were complex. I spent a lot of hours with various files cutting them to close tolerances.
I already took it on a suicidal spin across my driveway. I shoved in a seatpost, slipped in some wheels, grabbed onto the steerer tube and kicked off down the drive.