+1. JB Weld is the only solution that wouldn't require dismantling the front engine cover. As CharlieHustleX5 said, it's worth a shot, especially for $6. That piece has to go on flush, otherwise the starter won't line up properly.

The housing can be welded, but it needs to be removed. I wouldn't attempt to weld inside an engine compartment - too many things to ignite. But it's a small crack and it should be easily fixed. It might have to be resurfaced and the hole retapped, both easily handled by a machine shop.