Did you check the condition of the fuel in the IP chamber(any rust...gunk..sediments ..."resinification" there)?
Hm..we don't know the history of the pump/vehicle (somebody might have tampered with it in the past.). But if you have not disturbed the positions of the clamped connections for the plunger sleeves on the rack ...and everything is the way it is supposed to be I would do this:
-make sure the IP fuel chamber is getting fuel when I'm priming the hand pump. Having transparent fuel lines helps a lot! If in doubt,disconnect the fuel line on filter canister bottom or at IP entry and watch the flow. If flow is insufficient/absent with good filter the canister hollow stem might be plugged-clean and blow with compressed air..making sure no crap remains in the stem.Or...you can remove the by-pass valve and observe the flow there...
-if we're getting sufficient flow from the fuel filter canister outlet(or the by-pass valve connection)...we now need to make sure the fuel actually enters the plunger-barrel assemblies. I would not rule out the possibility of plugged barrel entry ports. You can remove the IP fuel chamber entry fitting and using a lit endoscope(or strong light..if the IP is on the table) observe the plunger rotation through the first element entry port as you move the rack .Tricky job though...or again,removal of delivery valve and spring will let you know whether fuel gets to this barrel...takes another set of copper washers...
-if the IP fuel chamber is clean and we're getting fuel in the barrels..then ,with IP fuel chamber free of air(do the bleed procedure described in the previous posts) we should see fuel past the delivery valves when we crank the engine. I would not count on hand rotating the crank by the 27mm. ballancer bolt... I'd connect the high pressure lines at the delivery valves and tighten but let them loose at the injectors...bleed the system...making sure I'm getting resistance while hand priming...then crank the engine with the starter or remote switch(with IP rack in the start position..yup,double check it's there..it might have been stuck again precisely at this moment
)...and watch for fuel spilling at the loose connection up there at the injectors(do this test first,before anything else described above).
BTW was there excessive fuel dilution of the oil in IP lubr.sump?