If you did not put the relief valve in the wrong place. A previous owner may have also done other things that are causing some of the present grief.

The relief valve was not improperly installed in the injection pump at a pump shop I would hope. If it was the pump was initially calibrated wrong. It would have still been sequentiall accurate though as long as the operational pressure was the same. Even at normal current presures it would not be this far off I would think.

That was a good find by you incidentally. The milli volt method is about the only sensible way I can think of in examining all this. There is something going on out there I do not totally understand. A few people have found that they did not have internal parts in their relief valves and I think there was one other oddball situation like you experienced more or less mentioned as well.

Now the hard part. When you get this sorted out I would drop the partial pan if there and plastigauge the number one rod bearing. Thats if you felt the injection pump had run at basically no fuel i pressure for a very long time. I see no reason that your newer engine would basically not be subject to the same issue as the 616. More a precaution than anything else. I only hope your car also has an acess panel on the oil pan like the 616 has.