Satan still trying to collect on his vehicle, but running out of places to hide!
While the head was off decided it would be good policy to change out the valve guide seals, polish the valves, clean the chambers and do some un-shrouding, etc and look what was hiding on the backside of the number 3 intake valve.
Never, ever have I seen a SOHC valve with a crack like that. This car has been chock full of surprises.