Let me throw this out and you guys can discuss it..There is no such thing as a freeze plug.The plugs you are speaking of are where the sand is dumped out after casting the block and the holes are plugged with the cups you are seeing.If they could get the sand out a different way you would not have so called freeze plugs.The manufacture doesn't care if you crack your block.Most newer engines don't have the plugs (like the rocket)due to modern casting processes.I have a friend that is using that port for water cooling a turbo hes rigging up. Should be interesting..Cracked blocks I have seen cracked in places other than where the plugs were..Wada ya think???Jack