After finishing the left aileron earlier today, I picked back up on the flaps.
I clecoed the left spar/rib clecoed assembly to the lower skin and checked the fit of the aft end of the ribs against the "rear spar" portion of the lower skin. The middle two of the interior ribs required 0.020 shims, so I fabricated two 5/8" x 5/8" shims from some sheet in my scrap pile.
I also fabricated four FL-708 spacers that will fit between the end ribs and the lower section of the upper skin. I just happened to find a 5/8" wide trimming of 0.025 in my scrap pile so it was a fairly simple matter to cut four 1-7/8" pieces.
I drilled the aft end of the interior ribs (including the two shims) to the "rear spar" section of the lower skin. I was going to drill the lower skin to the ribs and main spar, but according to the manual, drilling the skin to the spar includes the hinge. The drawing shows a dimension of 1/4" from the edge of the hinge for a hole location, but there is a note that says drill the hinge so as to line up the trailing edges of the flaps and ailerons, and maintain a minimum edge distance of 3/16. I obviously can't line the flap trailing edge with the aileron trailing edge yet, as the flap doesn't yet have a trailing edge (it's part of the top skin), and the ailerons aren't yet mounted. I'll consult others' build logs and VAF before continuing.
The four FL-708 spacers, and the 0.020 shims I needed for two of the interior rib aft ends.