The #8x1/2" pan head Phillips (sheet metal) sounds about right. What is on our '66 Newport are plain silver, not cad, even when the car was 1 year old. I believe the same screws are on my '67 Newport, too. Perhaps other model years are different, within the #8x1/2" sheet metal thread spec?
For an idea of how that spec looks, there's a "Standard Parts" section of the Chrysler parts books. EACH of those screws/bolts/nuts had a factory part number. GM has similar things, too, but in a separate catalog. Only thing is that some of those fasteners had a minimum order quantity of 100!
Just some thoughts,
CBODY67