OK, so, the settings I use in order to get “4 : 3 - like” display on 2560x1440 monitor, is :
custom_viewport_width = “1792” custom_viewport_height = “1435” custom_viewport_x = “382” custom_viewport_y = “-20”
Which is weird because according to aspect ratio calculators, the proper height for a width of 1792 should be 1344 (but it does not fit the overlay then). I don’t understand why, but my settings work.