The one plug looks like it is not firing - change it and see what it does.
If you're getting milky oil, that is a bad sign -- either cracked block or blown head gasket or both. What overbore on the block? Hopefully you have just a blown head gasket - usually the plugs will be washed down as a result.
If you find a blown head gasket, then switch over to the composite Best Gasket head gaskets - they are really good (other then when you need to change a set! LOL). If you need additional review, feel free to DM me or give me a call - be happy to try to be your "Virtual Flathead Doctor".