Main bearing cap broken how to repair

Mmmmm, you're not seeing what I am suggesting. Re-read my post to understand the reasoning... the Permatex #1 would in place of the pump gasket, between the pump and cap. It would not be of any use to reglue the broken piece in place.

I'm making not any guarantees; it is just that you sound determined to proceed as-is, and this is one suggestion to possibly reinforce the pump alignment.