I noticed that both the ArcadeVGA and Soft-15Khz offer video modes with 256 vertical resolution at 60Hz refresh rate as part of their 15kHz video modes.
Is that not too high for a CGA montior?
265 X 60 / 15720 = 97.7% active lines which only leaves room for 6 blanking lines.
Older games that used a 256 vertical resolution like Kung-Fu Master, lowered the refresh rate to 55Hz to compensate for the higher number of lines. Besides, you would want to run such a game at its original refresh rate since it scrolls so I wonder why this in not one of the built-in video modes in Soft-15kHz and the AVGA.