Most wins: As much I it pains me that it isn't the Steelers :-) This reference says it's the Cowboys.
"Q: What NFL team won the most games in the 1970s?
A: The Dallas Cowboys."
http://www.triviaplaying.com/44_Football_Questions.htm
Most SuperBowl wins:
"In the 1970's the Pittsburgh Steelers were football's finest, winning four super bowls, and earning them the title, team of the 70's."
http://members.tripod.com/~steelcitysports/seventies.html
"The 1970s were dominated by the Miami Dolphins and Pittsburgh Steelers, winning a combined six championships in the decade. Miami won Super Bowls VII and VIII, the former completing a perfect season, the only perfect season to date in NFL history. Pittsburgh won four Super Bowls (IX, X, XIII, and XIV) behind the coaching of Chuck Noll and play of Terry Bradshaw, Lynn Swann, and Franco Harris—each receiving at least one MVP award—and their "Steel Curtain" defense.
The only NFC franchise to win a Super Bowl during the decade was the Dallas Cowboys winning Super Bowls VI and XII."
https://en.wikipedia.org/wiki/Super_Bowl
