a peace sign, according to MY school’s 50’s/60’s/any other decade, will be fine for most of your classmates (if completely historically incorrect).
This link has some good information, too, about sixties fashion (I believe there’s also a link to the seventies). I especially like the a line dress/pillbox hat Jackie O ensemble. Or mod.
This link has some seventies fashion, the usual…disco, platforms, “ethnic” prints. All that good stuff.
Hope that helps :)