1440 is an anamorphic of 1920×1080. If you bring your footage into FCP correctly, it would have crated a 1920×1080 sequence. Assuming your footage is HDV, the best way to deal with the footage is to transcode it to ProRes. That being said, you can try to copy your original sequence, create a ProRes 1920×1080 sequence and paste that into the ProRes sequence. Render away export and you should have the correct result.
Steve Eisen
Eisen Video Productions
Vice President
Chicago Creative Pro Users Group