Ok, just for information.
The proper horizontal resolution to display a vertical game on a 4:3 horizontal monitor with the correct aspect ratio is 16/9 x height.
Example: 1942, 224x256 (256x224 vertical)
height: 224 -> 16/9 x 224 = 398,22 -> 400 (round to 8-multiple)
So the correct resolution is: 400x256
Or any multiple: 800x512, 1200x768, etc.