Cast iron is considered a non-weldeable material. It can be welded, but a cast-iron weld will not be as strong as the base metal. Therefore, it would probably crack again. Note, probably, not definately.
I would be inclined to replace it with standard. Branches tend to increase underbonnet temperatures, although there are ways to combat that too.
Mag ons ons kenniskry met lekkerkry aanhoukry.