Finished placing the center wing saddle and two 'C' supports. I cut a saw kerf in the edge of each wing saddle supports about an inch above the bottom edge. The saw kerf was used to set the level of each support, front and rear, using the water level. The saw kerf was also useful setting the trailing edge string use to locate the 'C' supports. After leveling, the supports were screwed to the corner blocks. All supports were set within +/- 1/16 inch from each other. The water level works really good for this.
Saw Kerf Level Mark on edge of wing saddle and water level mark
End View of jig after leveling
Aft Quarter view of wing jig with trailing edge string