First, the (c)1971 wasn't added until around 1974, which was also when the advertising card first appeared. The mini decks didn't get 'updated' with copyright or typesetting for quite awhile, but the advertising card marks your deck as mid to late '70s at best, and the box style also marks it as being early on, whilst later boxes have end tuck flaps.
Coredil mentioned the Blushing Fool... Do you know what this is (earliest decks printed can be distinguished by a mottled pattern, most notable on the face of The Fool). Check to see if your deck appears this way.
Also, I suppose we are assuming your deck is USGames and not Weiser.