Bofronado

I am looking at buying an 01 outback that the owner says needs a new engine because there was antifreeze in the oil. He has changed the oil to get to antifreeze out of the engine. My question is: Is this engine totaled or is it possible this just needs to have the head gaskets done like so many other Outbacks? I think I could ge the car for around $500, so if it is head gaskets, that is a deal, if it is engine, I need to run away. Any thoughts?