Diesel Bombers - Turning up 8.3 Cummins?

Hello again. A friend of mine has a service truck with a mechanical 8.3 Cummins mated to an allison automatic. I am guessing it weighs about 15-18,000lbs. It governs out at about 65 mph. I am almost positive it has the p7100 pump. How is the best way to go about giving it more power. Would you recommend sliding the fuel plate (forward I think), grinding on the fuel plate, buying a fuel plate, or some other means? Would a fuel plate work from a 5.9 cummins, probably not? I am guessing the factory hp is on the low end, maybe 225, and I can check. He wants to keep it simple, and I don't think he will need a pyrometer as it is an automatic, doesn't pull trailers, and doesn't want to bomb it. Thanks for the advice. Eddie