Incredible vintage 60s/ 70s? dress

Amazing vintage dress in a pale greyish-blue floral pattern. I can only guess as to its vintage. Late 60s, early 70s? Very cool looking exaggerated collar. Zip closure in the rear. Unlined. There are several minor stains/ spots that are barely visible and are likely to wash out - see photos. No size label, but fabric is stretchy. See measurements below. 16” bust across 14” waist across 23” sleeve length 44” length of dress from top of shoulder