blykins - it is thought that the engine did not have enough coolant in it to begin with. Scott then added approximately 3 gallons to the system through the expansion tank but not the block. The water pump pushes rather than sucks. Once hot enough (AIR) within the engine the thermostat did open and coolant immediately met an extremely hot engine - pressure build, steam is created and BINGO.
Power Surge - I'd think if Scott could just give his engine a couple aspirin to make the head ache go away - he would.
Scott's engine should be fine but it's a tough lesson to learn - especially on a brand new rebuild. It could have been much worse!
Scott had a great idea in creating a post that outlines the do's/don'ts with FE engines. Had he called me it's one of the first things I would have asked him about - often there's no replacement for experience and the school of hard knocks can be so darn frustrating, and expensive.