from that time still living:

AK: Gravel and Stevens
KS: Dole and Jim Pearson
LA*: Elaine Edwards (who took over when Russell Long died that year) and Bennett Johnston
IL: Charles Percy and Adlai Stevenson
MA: Kennedy and Edward Brooke
OK: Henry Bellmon and Fred Harris
OR: Mark Hatfield and Bob Packwood
TN: Bill Brock and Howard Baker

And the following states still have one living Senator:

CA: John Tunney
CT: Lowell Weicker
GA: David Gambrell (who took over after Richard Russell died)
HI: Dan Inouye
IN: Birch Bayh
KY: Marlow Cook
MD: Charles Mathias
MI: Bob Griffin
MN: Walter Mondale
NY: James L. Buckley
OH: William Saxbe
PA: Richard Schweiker
RI: Claiborne Pell
SC: Fritz Hollings
SD: George McGovern
VA: Harry Byrd
WV: Robert Byrd

Wow, that means 33 are still alive.