Here is where the repair ended up.
BMW corp. paid for half of the repair (my dealer called them about the situation). I'm not sure why BMW paid half. I have a few thoughts like 1. I had the extended warranty and it expired just a few months ago 2. BMW thinks this is is a chronic issue and they are trying to avoid a recall and upset customers.
Either way... the head ended up not needing machine work. So the repair was to replace all 32 valve seals. It was about 40 hrs work (their claim) and a few hundred in parts. The price was $5k, but with BMW paying about half I paid $2,600.