Sifo-Dyas,  but then they say that the character is not Force sensitive. Perhaps he  lost his Force ability? Maybe it's somehow related to the way the Force  has changed in the film?
But otherwise, he would fit great. He's Human, von Sydow's about the  right age, he had a connection with the Sith (Dooku was his friend and  he was an unwitting part of the downfall of the Jedi) but is not one,  was strongly precognitive and could have predicted and thus faked his  death, worked with the cloners on Kamino so he could have a fake clone  body to put in the crash of his ship for Dooku to recover, would be  significant to hardcore fans but not to general audiences like they say,  and would be a Prequel-era character with a reason to be fascinated by  Force and Jedi related artifacts. And he could have been hurt and  required the use of the cybernetics while being discovered during the  Jedi purge and hunted down.