Just heard back from the shop and they tell me that it's definitely a
blown gasket and/or cracked head. They haven't pulled the head yet
though.

I'm just wondering how common is it to crack the head on these
engines, when the head gasket goes? Even if they have to mill the
head they told me I'm looking at a ~$700 repair, which seems
reasonable. If the head's cracked... not sure I even want to think
about that.