Dave,
So far, I'm still researching, but the most promising solution seems to be buying SSF-6 rods and based on a YouTube video, thoroughly clean the connecting points, use a propane torch to heat the steel side to a dull red, let the flux flow off the rod, followed by the SSF-6. The horizontal position sounds logical.
Being a novice at this, I don't want to blow a hole in the tank. I guess the trick is to not heat the area to more than a dull red before hitting it with the SSF-6. I should try with some spare parts first.
Tony
P.S. Small world. I was born and brought up in Ottawa (Eastview/Vanier City), went to Lisgar, and have an Austin Healey 3000 BJ7, as well as the Jag. Now retired in Naples, FL.