Rise of the dead topics..
Another reason that most mortal combat conversions /emulators are a bit off is because the arcade hardware uses some unusual refreshrate and resolutions. 400x254 in 53hz.
Even if you double the refreshrate to 106hz most VGA cards won’t hit 106hz with out special refresh tweaks . So either its to slow or fast if you lock the refresh to 100hz or 60hz. Otoh, the minor frame "jittering" on 100hz isn't really a problem these days, it's just visible of you look for it in some scrolling parts.. or using advmame on arcade hardware.
As for the conversions.. well, PAL should have been the closest if the machine could keep up with the speed, European jaguar maybe?