Coolant in exhaust and spark plug holes

Last year I was driving my 68/72 MGB in a local cruise, in and out of 1st gear only. Took an hour to go a half mile. At one point as I started to come out of first gear it sounded like spark knock. Then someone pulled up next to me and said I was blowing some major smoke. Took me another 10 minutes to get off the street and when I opened the hood the engine was hot. I poured some water on the valve cover and it sounded like pouring water into hot grease. When I got home I filled the radiator (figured it overheated) but when I returned after a two mile test the radiator was empty. Filled it back up and went around the block, empty again. I figured blown head gasket and just replaced it but the car won't start and I noticed water/coolant coming out of the exhaust pipe. Took the spark plugs out and it is spraying water/coolant not gas at least it doesn't smell like gas out of the holes. Could I have a cracked head or block? If head, how can I tell or test, if block what now?

With that much coolant loss you should be able to visually see the damage in the head or the block. You will have to remove the head. If you cannot find the leak source take the head to a automotive machine shop and have it pressure checked or magnafluxed. If it's in the block it's probably best to find a replacement engine.

Clifton