The notion that shift blob and SK skillets, or SK skillets and large egg logo skillets were marketed simultaneously is what stands out. Never heard that before. My information, from a Lodge collector who has unfortunately since passed away, has always been that large egg logo didn't start until 1987.
The longer list says, "1965-1992 that's when they put SK, DO, Etc. the beginning of disa" The 1965 part I agree with. But then goes on to say, "The blob with a shift number runs those same years." I do not recall ever seeing any SK skillet with a shift blob.
Edit: I went through my photo archive and found a few 7SKs with blobs. None with "Made In USA", though, which I would think would have started ca. 1965.
Unfortunately creating more questions than answers for the OP.