Are the interiors on any of these speckled? Might be interesting to know which years used what kind of finish inside. The NOS Westerner I perved at Weber HQ has a speckled interior. Kind of like an old oven.
Baking temps could do a lot to change the final appearance of these finishes. When I did ceramics years ago, the same glaze could look quite different depending on where it was placed in the oven. Even side to side on the same piece could see variation in temps and change the color. I presume kettles are hung on hooks and moved through an oven on a conveyor line, but there still could be variations in temps - especially for these "custom" runs. It would be cool to see more photos of the old production lines running back in the day.