Be cautious about condemned engines! When I sold my previous boat the buyer had an engine survey and to my surprise the company said the engine needed to be replaced. I paid for a second survey and the engineer said nothing wrong with the engine but a slight oil leak which he fixed free. He also said the injectors had never been taken out so the first survey which quoted having done this was false.
A friend had a similar experience with the same company and then had the engine checked by another engineer who said it need some work but nothing major.
Get a second opinion from an engineer recommended to you, unless you know it is not working properly and why.