I drilled the inboard spar/end rib rivet holes in one FL-706A by marking a centerline spanwise across the long leg, clamping it to the spar making sure it was flush with the end, then match drilled through the spar. I drilled the outboard three holes by marking a vertical centerline and drilling the center hole of the three. I then match drilled the top and bottom outboard holes through the rib holes in the spar. I measured and drilled the middle two holes free hand. I designated this FL-706A for use on the right flap, and match drilled the spar for the 5 outboard holes.
I placed the left FL-706A back to back with the right one and match drilled the 5 outboard holes. I'll match drill the inboard three holes through the left spar after I disassemble that flap for deburring.
I then partially reassembled the right spar and inboard main rib to the top and bottom skins to final fit the FL-706B. I'm not sure what I did wrong, but the plate came out about 1/8" overbent. After correcting that, I drilled the plate to the inboard end rib and the FL-706A, then enlarged the aft hole to 15/64 and reamed it to 0.249. A 1/4" bolt fit just fine (I couldn't find the rod end bearing that's supposed to go here). I finished up by drilling a K1000-04 nutplate to the interior of the rib.
Setup to matchdrill a FL-706A to the right spar.
Both FL-706A's clamped back to back for matchdrilling the left one.