Left me tell you this was a right pain in the butt, but the end result is worth it. For anyone else doing this you can start with a top measurement of 40mm and a bottom measurement of 20mm, this will give you a good starting point on how far the top and bottom of the fairing need to overlap the side of the rudder. I cut the recommended 8mm out of the side of the fuselage on each side and then installed the rudder, using a cardboard template I positioned and taped the template which was the same size and shape as the provided fairing and then adjusted and re-adjusted it until it looked reasonable. Of course the cardboard does not have the same spring back as the aluminium but it works well enough, in hindsight perhaps a stiff plastic sheet would have been a better choice. Anyway its installed and it works quite well to seal the gap as the rudder deflects. Installing the top and bottom bolts is a challange once the fairing is in place.
