1. Scuffed, cleaned and primed the interfaces between the shutter valve doubler ring and the baffle.
2. Riveted (most) of the doubler to the baffle. I left the outboard column of rivets out for now, becasue I'm not sure if I'll have to disassemble the baffle again to do the cowl fitting.
3. Did another trial fit of the shutter. I ended up making two minor revisions to the butterfly valve: 1. I bent the lower edge about 15 degrees to better match the angle of the baffle bend and 2). I remade the outboard shaft spacer to make sure the valve will never be able to shift and scrape on the edge of the baffle.