I'd say the best answer to the question is that it might float upright. But it also might flip over. With odds like that I'd say egress training is necessary for any who do extended overwater flights.
I ditched an H46 under controlled conditions (power on landing...in-flight fire). As it took on water, it also began to roll. If left alone I think it would have been on it's side or inverted prior to the last piece of metal going below the surface.
Without floats...you're on your own. With floats, if they work you should be okay in advertised sea conditions and entries.