If it was really overheated, the head gaskets will show some bridging and if it got REALLY hot, the heads will show some warpage.
From what you're saying, it sounds like water got intot he engine when it was lying around.
If it was run with blown head gaskets the oil will be milky. If the water & oil are separated and the oil is dark, I'd say the water was introduced later, most likely from sitting neglected.
Pay attention to fastener torque as you disassemble, look at the bearings & journals, and you should have a good idea how much of a beating and/or maintenance the thing received.