ntsc_mode

The option documentation is properly formatted yet

Default: 0 Example: 1

Set to 1 to enable NTSC mode (60Hz). Most games are designed for PAL mode (50Hz), but some may be design for, or is compatible with, NTSC mode. You shouldn’t enable whis unless you know what you are doing. The default value is 0 (which means PAL mode).

Source: https://github.com/FrodeSolheim/fs-uae/blob/master/docs/options/ntsc_mode