I too have replaced stripped fiber gears for others. Both times the engine was idling when it happened. No damage, other than the gear. I did not remove the head. You already had the pan off to inspect the oil pump? Any pieces of pistons in the pan? You've got to take the oil pan off again to remove the timing cover. Shine a light up there and take a look see.

Rick


1939 Chevrolet Stake Truck