I took the comic out and really looked at those areas. I'm not sure what the spine discoloration is, but def not a stain or tape residue. Its not as noticible live. The back cover is really more problematic than the front. I have magnification loupes and I cant figure out what the discoloration is. It looks more like a focal dust shadow than a stain, but in a very small shape. The upper right corner looks completely normal and that may be scanner artifact?
That's good news.
Then I would think it's a solid 7.5.