[chiphead]

Mashed plug gaps usually mean the engine ate something. Usually a screw or nut. You'll have to pull the heads to confirm what it was. The electrical failure at the same time is weird. Possible starter wiring issue as well?

I agree on pulling the upper valve train first and working your way in. Usually when an engine eats something, It should still turn part way backwards, unless whatever it ate bends a rod. So totally locked up is either starter hung in flywheel or bottom end failure.