Short of trial an error with different housings, is there anything else she can do to check the block and the housing? A good housing on a bad block won't solve the problem, or maybe she can fix her current housing with the right tool?

Check with a feeler gauge, a la: Engine builder's handbook: inspection, machining, reconditioning, valvetrain ... - Tom Monroe - Google Books

Or a DIY honing plate or lapping plate? Something to ensure flatness?