I'll start with the usual "are ya sure you've got all the nuts & bolts removed?". It's been a few months but if memory serves there's the 12 torque nuts, then the 4 bolts under the towers, the 4 nuts in the spark plug recesses, the 2 external bolts(fore and aft), and the removal of the cam chain tensioner.
If this is a recent engine that you're tearing back into then it should come loose fairly easily regardless of what you torqued it to. Once certain that every nut and bolt is removed I'll grab the head by the fins and try to twist it back and forth before giving each side an upward rap with the palm of the hand.
I've sometimes had to use a wooden drift to pop the cylinder block loose, but never had to use one on the cylinder head.