If memory serves me right, we did this at CX on some of the Classics in the late 80's. I think the mod dropped the nose of the pod about 1.5 degrees to more closely align the thrust vector with the flight path in the cruise at LRC. We had a rather colourful Director Eng at the time who claimed full credit for the idea. He was such a character that I wondered at the time whether he bothered to clear the idea with Boeing (or CAD).
I don't know how successful the idea turned out to be in terms of fuel burn or undesirable side-effects. But nothing more was mentioned after a few months...