Thanks for the reply!
Yes, you're right. I need to use 576 vertical lines like this. Then I get the same result as you
5237x3491 -> 864x576
576 (Vertical) x 1.33 (4:3) = 766 / 1,5 (PAR) = 510 px tall (510/16=31,875, 32x16=512) -> 864x512 ->
720x512 (Resized to 720, MPEG has an embedded DAR)