I would never say he was conservative, but he sure was more right than most Repub politicians now.
However, the 1960s era liberal was definitely not an economic conservative. The Democrats of that era supported confiscatory income taxes, mandatory union membership, high minimum wages, and strict regulation of industry and commerce. Both the Goldwater and Rockefeller wings of the GOP were more free market oriented. The Rockefeller wing, ancestor of today's RINOs, did not want to repeal the New Deal or the Fair Deal. Even Reagan touched neither FDR/Truman era legislation, nor LBJ's Great Society and Nixon's EPA and OSHA. Ditto for Trump.
If JFK were alive today, and he would be 104 years old if he were, he would be at least a social conservative, unless, like countless other liberal politicians, he "evolved" into the liberal position du jour.