You have the height and width switched. NES is 256×240. However, the top and bottom 8 lines are usually black, so games have a 256×224 rendering area, which is then included in a 256×240 image, which is then stretched to 320×240, making games look like 320×224. There's no way to force a WiiWare game to emulate this, AFAIK.
Please I need help with this. I just homebrew my old 3ds console and downloaded a CIA file, but after surfing through for only 10 sec or less this appears. please can someone help me? Thank you in advance.