There is no such thing as a "Healthy" Itachi ... We can only go by what we see in the manga... "Healthy" itachi is a made up character you and the other Itachi fan boy use in a situation when you know Itachi is outclassed or can't win.
Even if Healthy itachi was real ... It wouldn't make much of a difference apart from maybe boosting his chakara from 2.5 to maybe 3.5?