So.. I started on my sign project the other day. I don't want to restore it, just make it presentable. This is my process, it's probably different from everyone else's.
Pic 1. I cleaned the torch slag off with a hand held grinder.
Pic 2. I found a piece of sheetmetal and trimmed it to fit by tracing the top crown and then I lined it up on the torched side and traced along the torch cut.
Pic 3. I welded it in and ground my welds smooth, I kept the heat low and used a wet rag to cool it, so as not to ruin the porcelain.
Pic 4. A little body work goes a long way. Primed and ready for paint.