Hey MBJ, what is the point of working in 4:3? Wouldn't it be easier to do it as 16:9 from the beginning? A dvd player would letterbox it on a 4:3 TV anyway.
Also, if you are just going to crop the black bars and resize back to 720x480 for the 16:9 version, you are essentially just stretching the picture, and this could be as easily done using the Zoom function on a 16:9 TV.
So the anamorphic version will not be any better than the 4:3 version, except you won't have to set your TV to zoom!