That screw you pointed to is the rack stop, this effectively adjusts the fuel delivery, when adjusting by allowing the fuel rack to open futher. this will not affect the maximum governed RPM of the engine, however if fueling is very lean obviously the load will stop the engine revving up to governed speed.
Really you need to check the valve clearences, though in my opinion its unlikley to be a problem, and intake exhaust for blockages then assuming ther fuel filters are clear and there are no other problems with leaking pipework make sure the engine can reach ~300 rpm more than the expected max on load speed on the throttle stop screw, then start fiddling around with this screw until you just get a little whif of black smoke under aceleration.
It will also be worth checking if there is a compensator device on the pump, and if it works, this will increace fuel with boost.(i cant see one)
diesels without a compensator can smoke fairly heavily when accelerating while the turbo plays catch up. it should be clean once the turbo spools up.
If you are unsure if you have over fuelled fit an exhaust gas pyrometer. do a google on EGTs I would also fit a boost gauge so i could see whats going on.
When pumps come from calibration they can be wrong, yours could be set to fuel a non turbo for example!
I am unsure why your rpm dips, maybe because of the hull shape and bite the prop has? or some anomaly with the fuel delivery, i think it requires more fiddling