After the dust settles on your block repair, if it still leaks you can use "waterglass," calcium carbonate, I believe, as a stop leak. It does not plug up heater cores or other small passages. The shortcoming of waterglass is that glycol-base antifreeze will render it useless. I don't know about alcohol, which was used before glycol.
I see you're in California, so if it doesn't freeze where you are this might be a solution.
Farm women used to use it to preserve eggs. It seals pores in the egg shell hermetically sealing the egg. They can be used months later without refrigeration. I am old enough to have used it for both purposes.
