The reason it could possibly be the culprit is there ain't nothin left. You said you had the head "fixed" what exactly does that mean? Did you have it welded up? did you get the valves ground? Did you have the surface milled? Please tell me you didn't do a bunch of work on a head and never had it checked for cracks. If you have a crack directly into the water right where the temp bulb goes that would probably do what you are describing. As the combustion pressure could conceivably just push the water out. Which leads me to the next point.
Look for bubbles as has been mentioned 4 times now, If you have a crack big enough to cause this condition before you have time to set the timing you will probably have water in the oil. You might have gotten water into the cylinder(s) which may or may not blow steam out the exhaust when you start it, and by now the spark plug(s) in the affected cylinder(s) could be starting to show signs of rust. If it is a cracked block, bad enough to overheat it this quickly, you probably have water in the oil.
The only other thing I could possibly imagine is (and like I said, I don't know all the combinations) is you put the head gasket on with parts of it covering the holes, or you got a gasket that somehow got some of the holes not punched out, (I have seen an engine in a brand new truck with no oil holes drilled in the crankshaft straight from the factory, things like this happen) or you got one for some other stage of evolution of these engines.
Maybe the simplest thing to do at this point would be to drain the oil and check for water.
The most likely scenario is you got a ruined engine, hope you didn't pay too much for it. The fella ain't gonna answer your call....
