I know there will be several differing opinions on this question, and although different they may all actually be right & good advice.
Heres my $.02 worth which may or may not mean squat so you will have to make the call on what you conclude is the right route for you to go after seeing a few different opinions.
Now..... my $.02 !
I have read and heard that some that say it's best to break an engine in with oil that is NOT synthetic because the rings have a harder time mating (wearing in) to the cylinder which actually require a certain amount of friction to accomplish, synthetic oil is a very slick oil that is designed to prevent friction better than conventional oil so by using it before the engine rings have seated good good cause the engine to take much longer to actually seat the rings than it should or it could be that because of the synthetic oil you may never get a proper seat on the rings and cylinder.
Now remember...... I'm NOT saying this is the gospel truth here, but it does make a little sense to me whether it is completely accurate or not, 'm sure there will be some that may agree and maybe some that will scream horse pucky...!
But I say if it were mine I would either break it in with Opti 2 at 1.8 oz's per gallon of fuel or I'd use a quality conventional oil @ 32:1 for about 150 miles or so that smy advise.
Now lets let the opinions fly..........LOL!