We are the worlds crudest amateurs when it comes to cast iron welding. Do a search on "welded sides on a Ford V8 60 Tin Side block" and hide your face in shame. The welds are PERFECT and this was years before TIG or MIG existed. It was also done on a production line. I have a friend that stainless TIG welds cast iron with great results but then he can also braze cast iron with like results. He filled a fire slot between the center cylinders of a racing block, run boring bar in each cylinder just far enough to clean weld and then just "brushed" the deck with a mill for gasket surface. Zero problem with the repair. I have sewn a number of heads, blocks, and even pump housings and always overlapped the previous plug.
