The radiator fans weren't coming on?
They should... at a coolant temp of about 205°F.

Had you replaced the coolant temp switch when you did the thermostat... the overheating condition would likely never have happened.

Assuming that only the head gasket failed, you may be in relatively decent shape.

But since the car was run at full hot, I'd have a machine shop verify that the cylinder head mating surface is square and not warped.

Worst case scenario, you may need to strip the head down and have it milled.

Worst of worst case scenarios, you may need to replace the cylinder head.