Unfortunately, I had already accounted for one of the short sections so after correcting for the furthest one I could only shave off about 4'. Then I gained the 4' to 5' back by adding the perpendicular corridor since I had originally placed a flat wall there in it's place. So no length change in my version
Just out of curiosity, what width are you finding the crosswise corridors in the painting to be? I've always guessed about 4' since the gaps seem too closely spaced to be the full 8'.
Also, after studying the GLW painting again, it seems like there might be TWO corridors crossing - one at the far end, one about half way up; with two pairs of doors facing each other. Is this what you saw as well?