I would say probably yes, but with caution regarding your youngest sister. If she knows that things like sex and death exist, and you could follow up the show with a family discussion of the themes/comparison to the movie, it would probably be ok. But yeah, it's definitely more adult than the movie.
(Most of) the sexual innuendo would probably go over her head and the profanity can be hand-waved as grown-ups-only words, but I agree with the posters above me that your biggest concern is likely "Hope." It's a brilliant piece of stagecraft and a highlight of the show but yeah, the multiple suicides (which are played for laughs at times but are also kind of disturbing) could freak out an 8-year-old.
But then again, your family knows her and her maturity level the best. It really is a great show and I'm sorry to see it never found its audience, and I hope that you guys (or at least some of you) can catch it before it closes.