Er, maybe I'm on the wrong track.
All of this seems too.. complex.
The solution probably needs to involve a dual sha256 too. That hint is still on the front post.
My pet theory is that the line on the right hand side of Wow.jpeg is somehow the answer, and the 51 character is just a red herring somehow. If it was just a transformation on the "private key" what was the point of the hidden swirls and lines on the image?