There are several companies that specialize in that kind of work. Do a search for "cast iron welding". Depending on your welding abilities you may want to tackle it yourself. I recently stick welded a manifold for a REO gold comet engine. I can do OK, but a coworker used a TIG to touch it up. A tig in the hand of an expert is impressive. Use 99% nickel rod and it is best to preheat. Don't grind a vee any deeper than 50%.
