ANY fussing with an injection pump requires very highly specialized tools and skills. I do not mean a diesel mechanic, I mean a specialized shop that only does injectors and injection pumps. Fixing anything on these is NEVER a do-it-yourself project.
This one needs to go to an injection pump specialist to see if it can be saved. Study the engine shop manual carefully to see if remounting and retiming the injection pump is something within your comfort zone before you take it off. If you take the pump off yourself, any local diesel mechanic can guide you to the nearest shop who can do this. In my experience, they are large regional shops, not little mom-and-pop places.
If I was taking the injection pump off for work, I'd probably take send the injectors along too to have them tested and adjusted. If they are good, the test isn't expensive, if they need rebuild now would be a good time to get that done too.