If your belly cramps your waistcoat style, this could be the one for you.
This black formal vest has satin lapels with square ends over what appears to be a heavy cotton. The back is also satin. The armholes are cut very deep. Two front fob pockets also have a satin edging. There is no front closure at all, so there is plenty of room to accommodate a fuller figure. No rear adjustment. Fully lined. There are no labels at all. 1970s-1980s?
Width at the waist measured with the front edges meeting is 56 cm (22"), but of course you will be able to wear it open