Time to drill the sub panel top flanges to the sub panel. I temporarily installed Van's forward fuselage skin in order to use the prepunched holes as guidance for where to position the rivets in my parts.

Marks transferred to the new sub panel top flanges.

After drilling the holes to #40, I positioned the top flange relative to the canopy skin using a couple .025 spacer shims at a few locations, then match drilled through the sub panel.

It took some adjustments of hole positions and the top flange itself before the left side top flange was fully drilled to the sub panel.