CONTRARY TO EXPECTATIONS of permanent youth and certain societal change, those who back in the '60s were exhorting us not to trust anyone over 30 are now themselves over 40. And an awful lot of people who've never hummed "by the time I got to Woodstock" are running the country.

However, according to Curt Smith, a speechwriter for Secretary of Health and Human Services Richard Schweiker and author of the recently published Long Time Gone: The Years of Turmoil Remembered (Icarus Press), a lot of '60s- era values have been absorbed into American life and, headlines aside, the citizenry is a lot less conservative, culturally anyhow, than it used to be. Smith himself is a 30- year-old and a conservative and says he would heartily like to see things otherwise. Long Time Gone is a ramble backwards into the '70s (which, as everyone knows, were really the '60s, so to speak) from the point of view of a young man whose current political idols are Ronald Reagan and Margaret Thatcher.

In the service of objectivity, Smith, who also wrote speeches for John Connally during his 1980 presidential try, talked to a wide range of subjects, newsmakers from the "years of turmoil." Though the book ends with a conversation with another figure Smith much admires, Richard M. Nixon ("I like him for his foreign policy," Smith told "Book Report," "and his affinity for Middle America"), it's some of the other dialogues which give Long Time Gone its curious flavor. After all, what other member of the Reagan administration has sought out Ramsay Clark, Betty Friedan, Julian Bond and Jerry Rubin for a chat?