I don't think that's enough time to get to the ferry dock in P'burg. It may work but everything would have to work in your favour and that's a lot to hope for. From wheels down you basically have 1 hour to get to the ferry dock and you are landing mid afternoon which could be busy. Even with carry on only you still have to go through immigration which could be a long line and you would have hope for the traffic to be moving with no traffic jams ( that's a big wish). Better have a Plan "B".