If you come across losing all compression after a sudden high rev and shutdown...............here's your culprit.
Sudden high revs usually after clearing a flooded engine or just over revving may cause the lifters to pump up opening
the valves slightly and causing loss of compression. Remove the valve covers, back off the rocker shaft bolts slightly until
you have compression and start. While running slowly tighten the rocker shafts until the lifters bleed back down. It's rare but
it's confusing and could lead to an unnecessary tear down. Good luck!!