It depends on the dimensions of the tank, but 260 watts is usually enough for tanks under 60-75 gallons. Some species of leather corals come from shallower waters and may require more light, but most will adapt to lower light levels.
If you can situate the coral below the lights, it should be fine. Decades ago, I've kept leather corals in (proportionally) less light then that and they did fine. Of course, a little more light won't hurt either
