This is a Basso that came in with a similar break on the drive side. It was sometime back around September and I posted pictures of the process. A cut to make the weld go all the way through the break in the drop out, and five minutes with a wire welder to do the weld. The DO got warm, but not hot where the brazed joint met the stay. I spent about an hour reshaping to drop out by hand and gave it some protective paint until further progress can be made. I left a little of the weld in the triangle of the DO because it only adds a bit of strength to the welded area.
As a younger man I did the removal and re-brazing of a broken Suntour like yours. The weld was far easier and I expect it to hold up to the wear and tear of daily riding. Smiles, MH

A standard wire weld that has been reshaped and given a protective paint until further work can be done.

You can see where the break was just in front of the masking tape. There is a slight amount of the weld left inside the triangle to add just a bit of support to the repair area.