This is very close to the pullover pattern that was so popular back in the 1980s because it was made all in one piece. It starts at the side with a chain long enough to go from the waist in front, over the shoulder, and down to the waist in the back. You work your first few stitches in ribbing (sc in the back loop), work down the length of the chain in your pattern stitch until the same number of chains is left for the ribbing and work them in ribbing. You will be working back and forth from side to side, hard to explain. Work until you have 1/2 of it done, then work the next row until you are almost to the center of the piece, work a chain the length of the neck opening, skip that number of stitches, and work in pattern across the rest of the row. The next row is worked as above, working into the neckhole chains also. Work until you have the same number of rows on each side of the neckhole. Then fold the piece in half across the shoulders, sew up the side seams leaving room for the armholes. Work a round of sc around the armholes and the the neck. That's the pullover. For the vest you would make the center chain long enough to go all the way down the front, turn and work back in the chains as established. We had made up our own version in my shop, but I doubt I could find our handwritten and sketched pattern in my now-closed shop. Here is the Leisure Arts version that came out shortly after ours. https://www.ebay.com/itm/Quick-Crochet-Vests-Leisure-Arts-417-/273609853187 It's the blue one. I don't remember if there is ribbing at the bottom of this one, but it would be easy just to change the first and last, say, 8 rows to ribbing.