Its good to be lucky - can't believe how much of the time you guys ask question and luck has it a car pops up locally to answer your and my questions
Anyway found a Late December (projected date) 69 original paint Dearborn example and the shop had started disassembling it ( allot of my pictures don't have the cowl cover removed) this week. It appears (will have to go back and correct my earlier statements to reflect this period of time) that the painter on at least this car did not black out the windshield lip (forward edge of where the dash pad would connect) to hod the body color around the defroster ducts and dash pad to A pillar molding. Don't not look nice but that is the way it was on this example. Did the same on my April car and I need to get back into that one to black those areas out since they jump out visually with an Orange car
How this manifested itself on my 69 Boss driver
Interesting that the April A pillar covers are shaped differently at that end
Anyway will post a few pictures to illustrate what I found .
Of course the area under the cowl cover would have the "zebra" stripes from the application of the Mach I hood treatment - unfortunately the example is from a non- Mach I
Hope this helps in your project