Well, if you take into account also the fact that the "monochromatic" photon (one that has a definite wavelength, or momentum) does not even have a certain posi

Well, if you take into account also the fact that the "monochromatic" photon (one that has a definite wavelength, or momentum) does not even have a certain position in space, the idea of its interaction with an actual (non-virtual) graviton near a mass located at a certain point in space will start looking problematic.