I have never seen paint marks like that before, but if those were out there because the original had them, could be to make sure line workers knew it was special? I really don’t know.

I found similar markings on my BE rear, though the stripes were front to back vs side to side. Also saw similar on a 9,000 mile unrestored COPO at Goodguys in 2019. First photo is from unrestored car, next are what I found on mine, third is my attempt at recreating the stripes.

Wouldn't those yellow markings on the pig,have originally been applied underneath the black overcoat?

Yes, I believe that is correct. I actually painted the black, added the yellow, then top-coated black over the yellow. I then took acetone on a rag and removed some of the black to let the yellow show through. Obviously not 100% correct, just my attempt at duplicating the look.

i'm working with a 69 camaro expert on this car who's name I will not mention as I do not want to drag him into any potential internet arguments. I asked him that same question. He told me to put the inspection marks OVER the black paint. he did not give a specific reasoning for it and it was impossible to tell on this axle wether they were under any black paint or wether it was on top of the black paint.

FWIW, I did not find any black paint under the yellow when I carefully stripped mine down. Once I got through the yellow, it was bare cast.

That's what I've witnessed on many as well.