I agree that 50k is nothing. But same applies to IP. It shouldn’t have needed to be rebuilt at that age.Awesome, and glad you’re feeling like it is getting better.
Yes, anyone that can rebuild an injection pump can also rebuild injectors. They may have a similar parts availability issue, but usually parts can be found. In my experience, the shop usually changes the springs and seals in the injector after cleaning everything, and they test each one on re-assembly for proper volume, spray pattern, and trigger pressure. It is pretty easy/quick, so it might be worth your time to get it done before the trip, maybe a 2 or 3 day delay.
With respect to adjusting the pump, did you loosen all of the injector lines at the pump before turning it?You have to bleed them again afterwards, but it should make the pump turn more easily because the lines pivot a little instead of trying to bend them.
50k on injectors is virtually nothing in my opinion, they could be gummed up. Run some really good diesel injector cleaner (I always used Power Service) at 2-3x strength and run a couple of tanks of fuel through it.