Well, after much procrastination and a major hangar move from Virginia to Ohio, the leading edge transition plates are finally in and cleco'd. Drilled as well.
Two ideas for next time: make sure the end-rib flange is fully bent to 90 degrees, and once the transition plate is positioned to have the 11/16" exposed, draw a line along the edge with a sharpie. Drawing this line allows you to position the rib vertically without having to line up the transition plate again.