Runaway engine damage 1.9dci

I am considering buying a laguna2 1.9 dci that suffered a runaway engine and now has no compression. I am wondering if anyone can tell me what is typically found in this case. Is there a good chance that it just bent the valves or do they often put holes in the pistons? I will try turning it over by hand and feel if it seems there are valve heads rattling around inside. If it feels smooth for two full rotations I might be tempted to buy it cheap. I have also read here that when the engine goes runaway it can burn the injector tips. How likely is that and would it be obvious if I pull an injector to see if it is burnt? I have many years experience in gasoline engine rebuilds while living in the US but now that I am in Europe I am getting my diesel experience. Thanks for any replies