I also asked the same question when I first was blessed with this virus. The response I got then was something to the effect of:
Yes, even if you have Type 1/2 genitally, it can be transferred to the other location. It's rare, though. That's because you're body has developed a defense against the virus which affects your whole body.
Since then, I've discovered that it's even more rare, if not virtually unknown, to have HSV2 orally. All the literature, and all the comments on this site, indicate that it's possible to have HSV2 orally. But it seems that that comment is more of a cover your butt comment. When I asked the board in general, nobody responded that they had HSV2 orally. Apparently it's REALLY rare.
So the answer seems to be, yes, technically it's possible. However, it's improbable.
That's what my reading has told me - I'd love to hear other opinions on this tho...