The rings don't look lifted.
The pistons, as someone else said, look detonated (slightly).
Check the deck and head surfaced to make sure they're flat. If everything checks out OK, prep the surfaces really well, lay down new gaskets and use new head bolts. Then use breathers in both valve covers.
I'm thinking since you still had "some" pressure in the cylinder, you barely blew the headgasket. And, as Jay said, make sure you REALLY tighten the intake bolts down good. Torque them down closer to the 20-24 ft-lb range. It also might be a good idea to get a new set of intake bolts too.
Joe