Stunning vintage 1960/70s brocade and chiffon cocktail dress

Mad Men chic! The peaked scoop-neck bodice of this dress is a black and metallic gold floral brocade, and the skirt is a flowy black chiffon lined with taffeta. The only tag is a size tag labeled 20 1/2. There is one small light mark, perhaps bleach, on the back near the hem, and the old metal zipper has a repair at the bottom but is functioning fine otherwise. The last two photos show the repair and that it isn't visible when zipped.