Hi. I have a 5.7L vortec that overheated from a closed thermostat. The temperature reached around 240 F, I continued to drive for about ten minutes. Pulled over, let engine cool down for about 10 minutes, then drove another 10-20 minutes. There is now white smoke coming from exhaust and a loss of coolant, as well as water dripping from exhaust.

Is the wall thickness between the heads' coolant port and exhaust port the same as between the wall thickness of the blocks' coolant port and cylinder ?
Or is it thicker or thinner?
Where can a person find the complete specifications of the engine block and cylinder heads?