I'm guessing a little bit of oil was getting in from the lifter valley. There was light blue in the exhaust but not a lot like you would get with rings being worn out.
I don't know what the cylinder pressure should be in an 8 to 1 compression engine, but what I am thinking might be a possibility is that #8 still has the proper pressure and the rest are low due to gasket leakage. If you look close the other cylinders have deformed the gasket as well.