Drilled two #40 pilot holes in the HS-405, but then used the HS-404 to drill the center two pilot holes because that is where the edge distance may become an issue.
Finally broke down and drilled after test fitting for two days. I was concerned that the un-drilled front spar inboard of the center rib would pucker by drilling the HS-405 first. Then I realized the plans are written that way for a reason. You work from the rear spar forward, and then when you get to the front spar you match drill that before match drilling the HS-404.
Kept the HS-405 aligned with the skin, drilled the #30 holes to the rear spar, and then drilled the #40 holes for the skin rivets.
