I have used a flame spray torch made by ESAB which is the only way I would repair cast iron. For more details on how it works you could go online and look it up. But I have had a lot of success with it. Basically it's a oxygen and acetylene torch with a built in hoper and when depress the trigger you start spraying metal which has the same properties has the cast iron base metal so it will cool at the same rate so you don't get any crakes. Its truly awesome. I know my company stocks them at www.airweld.net but you can find them all over. Good luck.
Wow, those things or over $3K.. Ouch. Looks just like a reg oxy/acet with a hopper.