It took a little while to figure this out. We cold not get the supplied material to fit while keeping it looking like the pictures in the manual. After looking at  other F1's  ... we noticed that our upper firewall was pulled forward to much in the corners. We needed to remove a lot of material from the rear edge of flanges, leaving less than 1" at the top (first picture below.) This would be ok if we were going to use screws and nutplates for the rear cowling attach as per the manual but we have decided to use Camlocs instead. These parts were remade with wider material which worked out much better (second Picture below.) The rest of the Boot Cowl fit up went smoothly and the skin fits nice.