She was a seamstress and actually sewed many of the "costumes" of the group.

This set is one that she wore during the '60s or '70s in that group.

Black maxi skirt with red sleeveless vest. Very versatile and easily accessorized to provide different looks. Since I grew up during that period, I can say it would look great with a scarf around the neck or a fantastic large statement costume jewelry necklace of the period.

Almost anything under the vest would work. Turtleneck, button-down, flowy pirate sleeves, or even tank would look great underneath.  This would look great for decades to come if accessorized nicely.

Since it's polyester, it does have a little flexibility. I would guess it's about a size small/medium in today's sizes.

Approx. measurements taken lying flat: