Most of the water movement would be due to the evacuation of the crater — the water in the impact area would go straight up as very hot vapor, and the surrounding seas would flow in from all directions to fill in the hole.
Obviously, an event of this magnitude would have a huge effect on the planet. I’m just not a good enough scientist to figure out how this event would trigger the Quaternary and the pattern of glacial/interglacial periods we’ve had since.