The electrolytic de-rusting process got the part down to what was left of the base metal. It was pretty ugly.
Here's the finished part after all the brazing was completed. Brazing was certainly a much easier option than straight welding, but still it resulted in some distortion of the sheet metal. I ground off the excess material and hammered any distorted surfaces flat. The Bondo stage and glazing putty is always the hardest for me. The Bondo sets up too fast, so I have to work in small batches. When it is sanded it always sticks to the sand paper. The glazing putty is easier to work with since it dries harder, but only covers small areas at a time. Altogether its not too bad considering what I had to start with. Its by no means perfect, but I did it myself, which is what counts for me. Its only the bottom, which is obscured when the engine is installed in the tractor anyway. You can't see straight into the shroud for this reason as well, so imperfections will be difficult to see.