That's a weird frame size/aspect ratio (both screen dimensions and delivery frame size), but it's projection, and projection can require different or strange frame sizes (check the 2k delivery specs again. It seems wrong).
If you create a custom frame size, you will get RT support in FCP. So I would cut in a 2K sequence, and do a matte in Photoshop to letterbox/pad the image to the correct display aspect ratio, that will help me frame up the shot in FCP. Then you can crop off the excess area in the image when you are done with the edit.
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