Hard to tell - original ones even in the protected area like the trunk still age and I've never had the finish tested nor know of anyone that has.
Would not trust NOS examples as they may have (plenty of examples where many parts differ) changed the specs or change the protective coat.
Not sure my pictures are any better than what you have but have never seen the outer surface that looks like galvanized - though in the same trunk space the trunk latch is easy to compare to.
How did you remove the white paint? Chipped off, scrapped, other method? Since this could contribute to what the surface looked like