It should have a Roosa-Master DB2 pump... there still really isn't much that can be done while it is still on the engine. There are shims inside the pump that limit fuel delivery as well as a "leaf" spring that also limits it. Both can be taken care of, but the pump has to come apart for that.
There is a little that can be done by tightening up the screw that puts tension on the leaf spring, adjusting the smoke screw, and advancing the timing. But that can get complicated as well, but with some patience and a little lost diesel fuel (some will spill out of the pump) it can be done by just about anybody.
Where are you located? Maybe a local shop can help you out. We've played with a few and the PTO clutch on most started to slip around 180 and there was a lot left in them... The limiting factor is the TO4 turbo, pretty hard to push any more than 230hp out of them.