I have never owned one of these vintage costumes before.
But when I saw this one in the original box, I decided I needed to make it mine:
I had to stick a vintage tin canister upside-down over the neck of the form in order to put the mask on. I have added some "hair", too, since taking these photos, so that now her hair hides the tin that is, essentially serving as her head.
(Hey, you can get pretty creative when you've got to work with what you have!
I found the canister at the same thrift store as the mask.)