welding cast iron

As was mentioned get a competent machine shop to do the repairs. I had a BB one which was broke in half. I had my local machine shop weld it and surface it, looked great, worked good and held up just fine. Once painted could not even tell other than one of the numbers being missing where the break/weld was

Broken completely in half is the best way. There are zero stresses in the casting when you are done, providing you can keep the entire area being repaired at least a dull red the entire time you're working on it.