Also known as Ghost Warrior. It’s an unfrozen 400 year old samurai in modern times, but he does look like a caveman when they bring him back and there is a scene where he is fascinated by a toilet. It’s from the 80s, though, not 70s. Below is a trailer:
Iceman (1984).
Could it be Encino man (1992), its definitely not the 70s but its about a caveman that becomes thawed and then goes on to highschool etc.
http://www.imdb.com/title/tt0104187/
Trog (1970)?
“Swordkill” (1984)?
Also known as Ghost Warrior. It’s an unfrozen 400 year old samurai in modern times, but he does look like a caveman when they bring him back and there is a scene where he is fascinated by a toilet. It’s from the 80s, though, not 70s. Below is a trailer:
Eegah (1962)
https://www.imdb.com/title/tt0055946/