The stock headers will easily support the weight of the bike with no ill effect. However, if you're not REALLY, REALLY careful, you could easiliy drop supporting it on a jack.
If you have to do things that way (I have many times in the past) use a piece of wood underneath the headers to spread the weight over as large a surface as possible, while protecting the headers from scratches as well. And if you can, use some other backup to insure that the bike doesn't dump... a friend, tie straps, something.