You could port and polish it. Just Google up port and polish a cylinder head. It is a marginal improvement in some heads. for other heads it is a great improvement. The 4.0 head already flows decent but there is always room for improvement.
"Taking care of our veterans is a cost of war. If you can spend six trillion dollars sending people to war, you can spend a few billion dollars taking care of them when they come home"
Sen. Bernie Sanders (I-Vt.)
If what doesn't kill you, makes you stronger, I should be able to bench press a Grand Cherokee by now!