As Carey said, and Fotoman expounded on, you must have a survey done to protect yourself. *I'd also suggest a diesel survey (probably 2-3 hundred more) to get a baseline for the shape of the Lehman. If there's excessive metal wear it will show then too. These are small prices to pay when you consider the cost if you buy a boat that needs work you discover after signing the papers.
Anyone trying to sell you on the idea of, "Just buy the boat and enjoy it" is either very naive to buying/selling boats or is trying to hide something. Only a good survey, by a reputable surveyor of YOUR choice, will tell the truth. If you don't know of one, talk to boaters in your area or check*http://www.boatus.com/insurance/survey.asp
*for more info.
Just my two cents.