Just looked at the parts manual for this tractor. It does have a mechanical fuel/lift pump. Sounds like you're getting enough fuel to the injectors as you described flow at the injector lines.
Were you able to check compression?
Yes, it does have the mechanical fuel pump, right under the injector. Have not checked compression as my checker does not thread into the port. Hard to hold the tapered rubber end sealed in the hole and turn the key at the same time.