If you ever had trouble finding the correct size and aspect ratio for images to be used in your HDV projects in Final Cut Pro, I'm going to try and help you clear up the mystery.
I generally edit in 1440 x 1080, but I like to start with an image size of 1920 X 1080, so I have the file at HDV's highest screen size if I ever need it that size in the future. I will then import the image into my 1440 sequence in FCP and open it up in the Viewer. Here, it will conform to the screen size by shrinking it 25%, so go ahead and bump up the size to 100%. Then enter a value of 33.33 in the Aspect Ratio field under Distort. Your image will now be the correct size and aspect for you project.