I suffered that type of failure on my 72 Vega. By the time I realized there was a problem, the block was already warping. The net effect was that the cyl walls went out of round. Pistons just can't go up and down when that happens. The engine just slowed to a halt, still trying to make power till it stalled.

The next day when we went to tow it home I tried to restart it by popping the clutch. I did manage to turn the crank far enough that after the head was removed I could see where the rings scraped metal off the sides of the cyl walls, for about an 1" of travel.