Vintage 1960's A-line long sleeve dress blue green white floral high neckline Lg

This retro dress is so beautiful. Rich blue and greens with white florals. Very figure flattering on. Stretch to fabric. Made in Canada by Montreal brand. Great condition minus some pulling/wear to waistband seam. Tag says size 16. I would say this fits Lg- XLG see measurements below. 20" armpit to armpit 42" length