JOY! I searched Amazon for for large clamps to squeeze the assembly in an attemp to line up the holes. I didn't find any solutions online but it finally dawned on me that I might be able to squeeze the assembly tightly together using nylon ratchet tie-down straps. I supported the aft rib flanges with some wood and tightened up the straps until I was able to get all of the clecos in the six outboard ribs. The inboardmost rib will be added later. I mounted the Left Leading Edge on the Left Main Spar and it fit very nicely. The W908 End Rib (inboardmost) and the W919 Attach Strip were placed, drilled and clecoed to the assembly.