A couple of observations for what they are worth. Firstly, the micro torch might be a bit on the small side for conchos larger then a quarter. never used one myself but have had students and friends that used them, They seemed to have trouble with larger and heavier pcs. Secondly, I personally would not use a soft plumbing solder to attach the chicago screw. I would prefer to use a high temp silver solder and the appropriate flux for the increased strength of the bond. and finally after silver soldering the chicago screw in place soak the assembly in a mixture of white vinegar and salt to chemically remove the residue of the flux after which you can polish, this called pickling and can also be done with commercially available pickling compounds.
A very nicely put together tutorial.