sarutobi, definitly:
1. orochimaru said to kabuto he did not have enough men to even think about attacking the 3rd, then after some thought he probably thought of edo tensei, sacrificed kin and zaku, and gained the power to face the 3rd ( 1st and 2nd aid, remember they are KAGE lvl )
2. orochimaru said that the 3rd was called as god amongst ninjas and the professor
3. sarutobi became hokage when he as damn young, he is 10x the genius itachi was, maybe 100x
4. when he was in the 2nd's genjutsu he didnt rely on sight, but on smell to locate him, who says he cant just do the same to itachi, or maybe something even more badass
5. itachi ran from jiraiya, even saying that they would either die, or he would die and take them with him, orochimaru knocked out jiraiya pretty hard in the sannin battle
6. orochimaru said that itachi is stronger than him, or something like that, but i think that's more because he is afraid of the sharingan copying his jutsus, i mean, how can orochimaru be able to fight jiraiya but, itachi cant

i can go on and on like this, but i think its pretty obvious that sarutobi would beat him, and if he was younger, he would slap itachi around