Here is what I came up with on the sail
Peter Powell was making these with plastic tubing and Strapping tape. All the kites had the same pigtails attached on the leading edge and the lower spine, one forward, one rearward. Train lines were attached to them / or for the lead kite the bridle was attached to the front set.
the strapping tape was used to secure the pigtails and the tubing. The spreader connection tubing has a brass washer on the bottom then the tape to keep it in place. The tube on the lower spine points up and to the front this is where the tails attach
The top leading edge has a 2.25 inch fold over on each side, the cutouts are 2" on the LE and 1.5" in the spine area
There is a .25" hem around the perimeter of the sail, the bottom has a 3"x2" extension that a piece of tubing was taped and rolled up for the bottom of the spine to be inserted.
the bridle has loops on each end and another short .5" loop at the fly line attach point, the finished bridle is 114" in length with the knot (of the top leg) at 56.5 inches
hope this helps
let me know if anything needs more detail Pictures: