I'm guessing that Winchester did not make the left hand model in 458 Win Mag? I see nothing out there about them.

They were not a factory offering.

I think the Custom Shop offered the .458 Lott instead.

George

I believe the largest caliber available in the left hand model was .375 H&H. I saw one in .416 Remington once but it used an unfired takeoff barrel from a right handed model.

This question prompted me to dig through an old Winchester catalog from the late 90's. I remember reading through it when it came out and saw the custom shop guns. They had the Custom African Express that came in a variety of neat DG calibers, and they specifically make mention of them in left hand. It was likely a pricey option, but I'm sure a few snuck out of there in 458 Win.

As far as a factory offering, Toomany Tools hit it on the head. The biggest they went in any of the LH guns (as listed, at least) was 375 H&H.