I'd say if you just weather it as it is - and weather it seriously!
Quite often, in those days, things like that were a reddish colour too, where they had been painted with red lead. When weathered, this ended up a dull, dirty-looking pink. I remember sheeting like that also, which was galvanised, thus a silvery colour when new, but faded and weathered to a drab dirty greyish colour.... any of those, I daresay, would suit - or even one panel in one, in the rest another! Cosmetic finish was low priority on such equipment.......