Vintage Custom Lilli Diamond Black Evening Gown

Vintage Lilli Diamond black satin evening gown with custom alterations; see photos. The sleeves are custom and there are two random hook closures in the zipper with no eye to hook into, so the bodice was somehow altered as well. There is no fabric or size tag. I am typically a size 12 and could not get it to zip past mid back, so I'm guessing this to be an 8-10, or medium. Please see measurements for best fit. This is in great pre-owned and altered condition. Approximate measurements laid flat: 57in length 18in pit to pit 14.5in waist 21.25in hip 20in middle leg slit No stretch