My 67 vert is in a lot of pieces so I cant go look. I'm trying to picture in my head how a shoulder belt would be routed and properly anchored and not interfere with snapping on the top boot/cover. Later models like the 73 Valiant we owned had plastic 2 piece bezels that finished a opening through the bench seat bottom for its lap belts. Maybe a pair of those would allow the shoulder belts to pass through the verts seat back rather than over it.