Goldbird, I looked through my generic Boeing documents (straight from Boeing, not specific to any airline) and the .78/290/250 chart is the only one I see. There is nothing in the Flight Planning and Performance Manual. I have the AFM for the particular series 757s that I was flying a couple of years back, and of course it has nothing, either, although I didn't expect it to since that data is not required for certification.
My experience working directly with Boeing (while on a minor management pedestal) was that they can produce a tailored output of that kind of data based on specific inputs. Sadly, they don't do that for anyone...only those folks who are making lease payments on one of their airplanes (and have paid for the service contract). Your company should be able to have that discussion with them, but you or your pilot group will not.