Good analysis. I was wracking my brain last night trying to make the part in front of me and my source pics match up. I see what you mean about the thickness of the raised border, and the rivets.
In fact, the other Hummel jack half isn't 100%, either. It, too, has a bit of a raised border in reference pics but the Hummel part has none.
The parts are close enough for my tastes, but you've raised some interesting possibilities. As you say, they either aren't from this kit or it was retooled. Anyone have a copy of this kit that was produced in '75 or so?