[Cin] removing letter boxing while preserving aspect

I have 3:2 content that is saved in a 4:3 frame with black bands at the top and bottom. I want to remove the banding such that the output is a 3:2 resolution clip WITHOUT DISTORTING THE ORIGINAL CONTENT. I've tried playing with the crop filter but the black bands remain, and the camera automation can remove the banding by zooming in, but then the left and right image sides get cropped out of the output. Is there a tutorial for this exact scenario?