Vtg 70s Jack Mulqueen Red Calico Rainbow Print Midi Dress Long Sleeve Belted L

Vintage 70s Jack Mulqueen Silksational Plus midi dress with long sleeves. V neck with rainbow stripe trim. Calico geo print in same rainbow primary colors on a bright lipstick red background. Elastic waist. Dropped shoulders. It came with a red thin belt with gold tone buckle. Not sure if it an original belt, but I will include it with the dress. Side pockets. Great preloved condition, no issues. Size fits like 10/12. Please review the measurements. Tried in size 6 and it’s way too big.