I had a yarn shop in the 80's and yes, these were very popular, I made several myself. Don't have the pattern anymore. You could use the pattern for a sweater started at the neckline and knit till it covers as much of the sweatshirt as you want, then sew it to the sweatshirt. I enjoyed the subject coming up again, made me smile. What goes around comes around, soon this will be in style again.