IMHO, the vendor that sold you the heads should bear the responsibility of replacing them, not another repair. Who knows if future head expansion and contraction might "uncover" another hole, even if a pressure test proves it's OK now (as it has before). In addition, I would think all gaskets and supportive materials should be a part of the restitution. Labor would be negotiable. I'm a small business owner myself and sometimes you have to dig deep to make it right for the customer, even if it wasn't the result of company negligence.
Another thought. Water running down cylinder walls has a tendency to "wash" off cylinder wall lubrication. I would want to inspect pistons, bearings (
oil emulsification) cylinders and all journals prior to running it again, essentially a total tear down.
I'm sorry, I just think you're due much more that over-the-phone counseling and "mail order" spot repairs. If it were me I'd pull the whole motor, crate it, ship it up and let them know to ship it back when it's tested and 100% again.