Thanks for David Wymore again for letting me scrounge an injection pump off one of his parts trucks.
I ended up taking it apart to find a damaged camshaft and boost pump drive shaft sheared off. But the hydraulic head looked good.
So I disassembled my trucks pump, all new gaskets, swapped camshaft piston from David's pump in since mine had a score from hitting the plunger button. I also found my advance housing had a badly kinked spring, I also reset the governor spring end cap clearances to spec.
Roared back to life just as the batteries pooped out. A little idle adjustment and 20 mile test drive. It has no more surging, goofy rpm fluctuations. It runs better than it probably has in years.
Next up, god willing....clean up axle shafts and install to finally get some wheeling done.