Which is the closest train station to Tianjin Port that has high speed trains to Shanghai?

We are arriving in the city on a cruise and are then going to Shanghai. We are thinking about using the high speed train (G class) rather than flying to Shanghai.
How long would it take in a taxi to get to South railway station from the port?
How long would it take in a taxi to get to main railway station from the port?
Are taxis readily available at the port or would it be better to organise a private transfer/shuttle? We do not wish to catch local buses or trains?