Have been out of town for several days—gave me some time to think about drilling the rear spar. Today, I checked and re-checked. Then I checked it some more. Both wings read 0.0 on the level when checking incidence. I have a 1/16” forward sweep on both sides and both tips match in height within ¼”. I finally got up the nerve to drill the “all important” hole for the left wing rear spar attachment. I verified all of edge distances then used a spring loaded punch to ding where I wanted to drill. I used a 1/16” to deepen the newly indented spar stub. Next, I used a 1/8” drill with a guide block and then reamed it to #30. I inserted a long AN470-AD-4 rivet from the front side to keep everything in alignment. Next, I used a 3/16” drill and guide block. The drill bit pushed the rivet out the back as the drill moved forward. From there, I kept enlarging the hole—used ¼”, 9/32” and “N” drills with guide blocks. I inserted a .3115” reamer from the front so that I could pull the reamer thru the hole to the rear. The .3115” is actually a 9/32” “undersized reamer”. I ended up with a nice straight hole—I pushed the bolt thru by hand—nice tight fit. Tomorrow I’ll repeat for the right side. I want to re-check all measurements again and if necessary, I can adjust the right wing slightly to match the left.