Time to start taking off the side skin. But first I saw these four holes that apparently get used later with the air vent bracket F-937. But from reading about their use I have decided to drill and dimple now. There is a chance I won't use them and just have to fill them with rivets. If I do use them I can still match drill thru the holes.
Then I enlarged the hole for the flap actuator arm. I searched a bunch on Vans Airforce and there is a lot of material about making this hole for the flap push rod. Bottom line is make it later when you are installing the flap mechanism and push rod so you can custom make it for the push rod.