He does have a good set of eyes on him, was going to say cylinder 3 looks very wet but didn't notice the crack. But as you mentioned the anti freeze answers that one.
Don't know if you've read my project thread, but I learnt the hard way with my block after buying a standard set of pistons. similar to yourself cylinders looked fine, honing marks, no visible damage, all pistons and ring were intact and didn't point towards any problems, however had the block sent off for peace of mind as couldn't indentify a problem. Turns out one of my cylinders had ovalled and I required the block being machined and had to purchase another set of pistons.
Actually ignore all of that have a set of pistons for sale if your interested lol.
Don't know if you've read my project thread, but I learnt the hard way with my block after buying a standard set of pistons. similar to yourself cylinders looked fine, honing marks, no visible damage, all pistons and ring were intact and didn't point towards any problems, however had the block sent off for peace of mind as couldn't indentify a problem. Turns out one of my cylinders had ovalled and I required the block being machined and had to purchase another set of pistons.
Actually ignore all of that have a set of pistons for sale if your interested lol.