Using any engine oil that is within the manufacturers recommendation of viscosity will be fine.
There is some controvercy about using a full "synthetic" oil for breakins, but it is my opinion that the concern is way overblown. More rumor spread by the Harley crowd than anything else...
And apparently some mfg's agree with me too, as they factory fill their bikes with "synthetic" engine oil.
Besides, the term "synthetic" is pretty much useless in the context of maintenance, as the term is really only valid in the context of marketing and advertisement.
Use any engine oil with the grade and service rating the mfg. recommends and you will be fine.
Always change all oil out often, especially one that is being used for breakins. You want to get the initial wear metals out of the engine as soon as possible.
I suggest dumping the first fill at about 1-2 hours run time.