Main bearing cap broken how to repair

Imagination is a good thing, not many people have it ;) but if one is really concerned here, perhaps you could drill a short 1/4" hole in both cap and pumpbase and install a dowelpin.
About the only thing I could see would 'notice' if the pump has moved a thou or two, is the intermediate shaft bearing.
I believe there's enough 'joint' play at the intermediate shaft at the pump end that a very slight misalignment wouls pose not much problems.