Vintage Lace 1950s Cocktail Rayon-Acetate Dress Tagged Size 9 - ILGWU Union made

Vintage longer (tea length?) 1950s dress tagged size 9, but I can't get it zipped, so I'm guessing it's more like a today's size 6, very slender fit. Measurement at bottom of bust is approximately 28 in to 29 in with 11-1/2 in from the top of the strap to that point. I bought it from a going out of business basement sale at an old dress shop in town, vintage new, thinking I might wear it someday and now I'm too big. ILGWU Union made. There are discolored parts on the lace as shown in the photos. I understand that can be taken out with lemon juice and baking soda, but I'm not going to attempt it. The lace has beads and sequins and the beads are in great condition but some of the color has come off in tiny flecks (from age?). Tag says 68% rayon 32% acetate. It's a thicker fabric in a mint green, slanted toward the teal side; the best representation of actual color is in the close-up photos. I'm 5 ft 6 in tall and the length is about three to five inches above the ground when I am flat-footed. I have a dog in the house, but he doesn't wear my clothes or shoes 😊 Seriously I do keep a very clean house, though, and it is most definitely smoke and cat free.