In order for the leading edge and the dimpled skins to fit nice and flat to the spar, the spar had to be countersunk for the dimple. I also deburred, both inboard and outboard top wing skins. I also lightly countersunk the end rib of the fuel tank for NAS1097 rivets to secure the reinforcement ring/nut plates. Both end ribs for the fuel tanks had to have a hole drilled for the vent as well, opened the holes up with a unibit, this location is approximate and was drilled looking at the plans. I also installed the nut plates for the fuel sender in the cover.
The wing walk doubler received the same treatment. The wing skins had to be scarfed at the joint so they could lay fairly flat with the leading edge skins. All edges were also given a slight break to make them lay flat after riveting.
As you can see, the fuel sender will have a dedicated ground with a wire ran to the main aircraft ground bar instead of grounding to the air frame. I also decided to replace the Phillips head screws with Allen cap screws for ease in the future. A ring terminal and a lock washer with inward teeth will bite in for the ground.