I'm really surprised it has a 6.2 The military swapped most out for the 6.5 some years back. I remember we could buy a whole drop in 6.2 for under $400 back then. Cheaper if you could buy a semi load of them.
You *can* hop them up a little bit, but really it isn't worth the time and energy to get to any real power, plus Stanadyne/RoosaMaster pumps can only put out so much fuel.