Woman's Vintage Button Up Short Sleeved Shirt w/ Hand Painted STP Logo

I believe this is from the 1970's. According to the label 65% dacron polyester 35% cotton. The STP logo is painted with liquid embroidery ball point pens. Label indicates a size 34? I would say it's a small inasmuch as it's 26" from top to bottom & 20" from pit to pit. Very unique shirt.