Having to reevaluate earlier statements and findings with the additional new examples that I've collected since I posted earlier comments. Happens
Have cars as late as mid-July built at Dearborn with no black on that thin upper interior cowl section where the upper part of the dash pad attaches so can't be certain if this was (at Dearborn in 69) connected with a production period or the result a particular painter or shift
Here are two examples
First one where the black appears to have been applied through the windshield opening from the front of the car after exterior color was applied
And of a A pillar section where they may have blacked out the interior vent area then up and onto the upper A pillar/windshield surround
Hope this helps as I don't have allot of examples with the black out detail showing/present