Some won't even touch cast. The ones that do would be pricey. It would only be a deal if you could do it yourself. You have to preheat, postheat and buy expensive nickel rods. You could try it cold and only weld a little at time allowing to cool in between. Then theres the old redneck way; hit it with 7018 and hope it holds! I've read a bunch on it, but it looks like a huge PITA.
The bell housing is aluminum, any one with a tig welder can fix it. Hardest thing to fix cast is exhaust manifolds because of the heat cycles.