Vintage well-made porn: 'Insatiable' (1980) with Marilyn Chambers and John Holmes and others

There is a very good blowjob starting around 18:15 but she doesn't swallow. She overhears another couple later where there is another great blowjob.

What can be seen as a major fault in the movie is there is no clear instance of Marilyn climaxing. She comes close, particularly in the final scenes where three men and a women pleasure her in the mental sexual fantasy she is masturbating to. Which is the point of this movie, she gets lots of sex but doesn't get satisfied even in her imigination.