I adjust the image so the 16:9 image fits inside the 2.35:1 screen adjust vertical lens shift if you have to, save the setting as 16:9. Then I zoom the image so the 2.35:1 image fills the frame and only use the horizontal lens shift to make it fit on the sides. If it isnt correct on the vertical axis use the lens menu vertical adjustment not the vertical lens shift. Once the image is correct save it as 2.35:1.
Good movies are as rare as an on topic discussion.