It's more difficult to say if they don't know each other's abilities. I would still probably go with Hiruzen-- Enma can attack without being scratched in rod form, and Hiruzen has stuff like mud wall to keep his distance even if he didn't know Hidan's abilities. In the case Hiruzen is scratched, Hidan likes to toy with his victims so long it would give the old man time to death reaper seal them both to make it a draw. So imo in no scenario would Hidan win.