I did a post on the idea of how aurochs-coloured Chianina might look like a while ago. I did drawings by tracking out photos of a Chianina bull and a cow and coloured them in the wild type manner. But the drawings in the first post were rather sloppy. So I did new ones a few days ago:
Original photo of the bull and the cow.
Colour is one of the most prominent traits of an animal that leap to the eyes when having the first glance at an animal. A completely striped donkey would look more like a zebra to us than a donkey, and vice versa. And an animal with aurochs-like colour but otherwise not many aurochs traits might look quite satisfying because that trait gets much attention. This is the case in for many Heck cattle that would otherwise look nothing like the aurochs.
And the reverse is the case as well. A "wrong" colour might make the animal appear less aurochs-like than it is, because it distorts the image as a whole. So I tried to imagine what wild type-coloured Chianina would look like, and how it would accompany with the aurochs-like proportions and slender body shape the breed usually has.
I think that wild type coloured Chianina would be quite aurochs-like. What would still be needed of course are horns of desired shape and size, they would also need larger heads with more elongated snouts (usually), as much as bigger humps. For cattle to be rewilded in colder parts of Europe, they would also need longer and denser winter coat. The winter coat of pure Chianina is sufficient for Central Europe (the Chianina in the Lippeaue do just as well as the other cattle in the reserve), but I think that a winter coat like Hungarian Grey, Heck cattle and others have is what can be considered the ideal case.