Agreed - if you have pictures of the original paint taken of these parts just reproduce what you found. Often the application could produce shadows on the back side from the edge details (mounting tabs and such) while other times the painter got more carried away and applied more paint
For others that may pull this thread up in a search here are some examples. Though some of the pictures may be from 70 also or from a different plant (labeled to indicate) they all work to show the variables and applications that can result
From a 69 Dearborn
70 Dearborn Notice the spray shadows produced
69 NJ
As for the cowl it would normally have body color along the firewall to cowl area up. As Armond mentioned each plant at a point started applying engine compartment black above that seam/edge so don't be surprised by the body color and look towards when the car was finished and use that as a guide as to painting or not painting black above that point
At this point a November Dearborn car would typically be body color there as mentioned above