I have never heard of a French Top. Are you sure that is not a reference to a bikini? LOL! As far as turning your fiberglass top into a Carson-style top, I did so for a '29 roadster I had ten years ago. I glued quarter inch foam to the outside of the top and then took it to a friend who does upholstery. He sewed fabric and covered the outside of the top. I covered the inside myself with the help of a seamstress acquaintance of mine. I started by making paper patterns for the inside. I ordered some auto interior ceiling fabric which come with a quarter inch foam backing. To start, I cut out two of the pieces allowing some extra for the seam, fitted them, and then had my seamstress sew them together. Then I cut one more, fitted it, and had her sew it onto the pieces already fitted, and repeated the process. Then when all of the pieces were fitted and sewn together, I glued it into place using 3M #90 spray glue. I had piping made prior to installation, and glued it in so the ceiling fabric edges would not show. It looked quite nice when it was complete.