Thanks for your answer to my query. Despite the fact that Utt. 574 seems to have been a bit garbled by an AE copyist or two, it is still possible to get a reasonably clear sense of what was intended. Unfortunately, your interpretation seems to fall no where near this, but no matter. I'll address mostly line 1487.

Mercer, who I believe you are quoting from, has it almost about right here: "Thou art standing, Osiris; thy shadow is over thee, Osiris" - except for the fact that he translates the word Shwyt as "shadow", when it actually has more the meaning of "shade" or "protection" - as implied by the S36 glyph. The image here is of the deceased King, here referred to as the resurrecting "Osiris", ascending to the northern polar region where this resurrection will occur. Above his head as he ascends, there is his "shade", providing him with protection from the strong burning heat emanating from the god at the center of this polar region. This "shade" of protection is for the deceased King (Osiris), not for Atum. If anything, the protection is protection from Atum, not for Atum.

In addition, Mercer misinterprets Sethe in regard to his "Mooring Post" translation. I believe the image here is of the deceased King on his voyage to his final resting place (in the sky). The boat's anchor is weighed and the boat is loosed from its moorage. The boat is what is "great" here, not the mooring post. The djed pillar was likely a post on the boat to which the mooring rope was tied, not the mooring post itself. See related imagery in Utt. 532.