720 x 576 is not square Pixel, it is PAR:16x15. you need to convert it to Square Pixel (PAR: 1x1), which would yield a resolution of 720 x 540.
you can use Hybrid for this Read here
Or select Square Pixel Type in TVAI.
Select Custom Resolution when you ready to upscale (in case you converted the video 1st in Hybrid) then you will have slightly smaller side bars and larger picture frame in Full HD (1440x1080 / 4:3).
