At 320x240, you have no room for a stylish health bar. The text overlaps. The portraits look like postage stamps. At 1280x720, you have too much room. Your background art needs to be massive. Your loading times suffer.
A deep look into these screenpacks reveals a reliance on specific scaling and coordinate systems defined in the system.def file. mugen 1.1 screenpack 640x480
These control the "In-Game" UI, including lifebars, power gauges, combo counters, and "Fight/K.O." animations. 3. Technical Configuration ( At 320x240, you have no room for a stylish health bar