Decided to use #8 screws and platenuts instead of #6 to attach the glare shield. Updrilled the shield and stringer attach holes with #19 bit and then drilled the longerons for #8 platenuts. Some locations required single tab platenuts. I countersunk the nutplate rivet holes and will screeze solid rivets to hold the plates in place.
I originally planned to use #6 screws but they seemed a bit small and there was plenty of room so went with #8. I had ordered extra #6 nutplates but now I am short #8 plates so l will need to order again. The #6 screws would have been OK, stronger than 1/8" pulled rivets. #8 screws are also a bit easier to install and remove and less apt to strip the heads than a #6 screw.