Interesting idea, Whitedog, however there has never been any coolant leaking out of here before. I have had the truck since 2002, had a rebuild in 2006 and just had a valve job done as I dropped a valve seat. It has had a Clifford manifold on it since I have had it. Possible it had a plug that came out during the revalve but I don't think so. No leaks out of the other two holes under the other intake ports, either. It has been suggested to put a 1/4-20 thread in it and use a set screw with Loctite to seal the hole. Just not sure about the coolant issue, though. I have no idea about the cooling jacket, etc.
