The engines could need a complete refresh if they werent fogged prior to storage, even then, they have been sitting for 10 years, who knows what is living inside them. If it turns over i would be surprised, more than likely the rings are frozen to the cylinder walls. I would take the plugs out and see if you can turn it over by hand first.
Hopefully it didnt ever have a drain plug in it for any length of time, otherwise all the water just sat in the bilge for who knows how long.
It will need a ridiculously thorough survey before you make any offer, and even then, it should be a low offer.