The factory drawing for both the cowl, radiator support and pinch weld area called for the areas to be painted with either blackout paint or Organosol. I have not found the original formula for the blackout paint and I would personallly not used todays mixture of Organosol. With that said the blackout paint was a dull or flat black. The reason for the cowl being painted was to reduce glare onto the windshield area and the pinch weld area to cover up the uneveness of the drain areas. The drawing even makes mention of the pinchwell area being painted with a brush.
Organosol on the cowl.