Very hard to advise from here. If the engine has been sitting that long that the engine is that gummed up, you could have rust in the cylinders, the starter may be just marginal and needs rebuilding, you may have put too much diesel in the cylinders that when you put the injectors in, the pistons are hydro-locking. Pull all the injectors and turn the engine over to expel any fluid that may be on top of the pistons.
Were the injector tips rusty when you first pulled them?
You may have to pull the head to see what you are dealing with.
You may get away with pulling the injectors and turning the engine over with the starter to polish up the cylinder walls, cross your fingers and hope for the best. When you said on of the valves was stuck, this leads me to believe that there is quite a bit of condensation in the engine and rust in the cylinders.
No way to tell what you have from here and no idea how much you want to spend to really give you good advise.
Also, I wouldn't spend money on the starter until I knew what condition the engine is in.