As others have said, 4:3 is 1.33:1, 720 x 480 is 1.5:1. Further, 16:9 is 1.77:1. All NTSC DVDs are set to display 720×480 regardless of the source aspect ratio. There’s a flag in the DVD coding that’s set to either 16:9 or 4:3.
Check this solution to the cutoff problem (which I’ve encountered):
If shot in, captured and edited in 4:3 and there is cutoff, the pixel aspect may be incorrect in the conversion from the editor into the file used to create the DVD. The Pixel Ratio should be D1. You might have to play a bit. Try exporting a small section.
Keep ’em flying.