While Danzo doesn't scale too much behind, due to his fight with Sasuke, I don't think you can get around the fact that he is ultimately beat by the Raikage in stats, especially given the fact that he can boost himself with V2 and the like. Having Izanagi and Koto feels like it would be pretty essential for Danzo to win here. Though, the Raikage comes off as a little dumb and reckless, I don't think it would be impossible for Danzo to catch him in a genjutsu....
(also, I do believe that a Prime Danzo who scales a good bit beyond the Sanin does exist, but since we have little to no info on that, I don't want to get into fanfiction tier headcanon, but Danzo is portrayed as one step behind Hiruzen, not 10 steps, he was likely strong before he stole Shisuis eye, which just helps him maintain Kage level strength in his old age)