The 70s had great cinema. The Godfather, The Conversation, The 7-Ups, The French Connection, The Driver, Taxi Driver, Deer Hunter, Chinatown, Jaws, Young Frankenstein, Alien, Dirty Harry, The Man Who Would Be King,..the list goes on and on.
I will not dispute that, some of my favourite films are in your list, however in general period pieces in the 70's were lacking in detail when it came to hairstyles.