I am about to go and look at a boat that been sitting on dry dock for about 6 years, it has 2 DD 6v 92 with about 200 hours since overhaul, the owner began a restoration but could not finish for various reasons, the boat is out of the water, so at this point I will not be able to attempt to start them. What issues and problems could an engine sitting for that long could develop, and what should I look for ?Thanks for all the help.