For those about to drill the spars to the inserts, I have a small detail that might help. Consider the holes on the top of the spar. The forward row of holes can begin either 2 inches from the inboard end of the insert or 4 inches in. The same is true for the bottom aft row of holes. Note that if both are set 2 inches in, the rivets will be diametrically opposed from each other. This will make it a little hard to pass the ribs over the rivets. This situation can be avoided by setting one row in 2 inches and the other at 4 inches. It's a small thing but it will help.