This doesn't exactly follow the POD, but still it prevents Heinz's death and puts him on a path to the White House:
In 1964, Mo Udall runs for the Senate after four years in the House. He narrowly wins the election and is re-elected in 1970. As a US Senator, he has more institutional support and name recognition than in OTL 1976 and this allows him to defeat Jimmy Carter in the Democratic primary.
38. Gerald Ford (1974-1977), R-MI
39. Mo Udall (1977-1985), D-AZ
40. John Heinz (1985-1993), R-PA
Udall chooses Carter as his running mate and the Democratic ticket unseats President Ford in the general. Udall succeeds where Carter failed on the economy: he closely works with Congress to pass an economic stimulus, maintain price controls on gas, and enact a universal healthcare program in 1979. Udall appoints Volcker to the Fed in 1978, a year earlier than Carter, and despite an economic downturn in 1979 the economy is improving again in 1980 - just in time for Udall to win re-election over Ronald Reagan.
In his second term Udall survives an assassination attempt but a recession breaks out in 1981. The Republicans make gains in 1982 and Pennsylvania Senator John Heinz wins a second term in a landslide. Handsome, articulate, and compassionate, he wins the 1984 Republican presidential nomination and narrowly defeats Vice-President Jimmy Carter to become America's 40th Chief Executive.