Your engine will break in normally with synthetic. And...
This is a common misconception. Synthetic oils will not harm your engine during break in. They are designed to work in your engine and as long as you use the right weight of oil you will be fine(if they did harm the engine do you tihnk BMW would ship their cars with syntetic?). This was something that they pounded into our heads at school when I was in there to become a mechanic.
I have a friend racer/mechanic on Corvettes and GM ships those with Mobil 1 too. However they did change their cylinder honing to do so, or at least that's what he reports. And he would know .. He's an insider with the GM factory crowd ..