who would win posin vs. bite

Given that the komodo dragon lives in SE Asia and alligators live in the americas, we can't test the hypothesis, but my guess would be that an alligator would easily win, as komodo poison takes days to act, whereas a big ripping bite from an alligator is pretty instantaneous.

My money would also be on the alligator, but only just.  Venom is only a small part of the Komodo Dragon's armoury: mechanical damage from its bite is likely to be a much more important factor.  Their bites have been measured as exerting relatively weak forces, but they have tremendously strong neck-muscles so that once they get their teeth into something they can tear it apart very efficiently.  Also, the Dragon, being a monitor lizard, will have a somewhat higher metabolic rate than the alligator, which means that it will have more stamina.  If the fight doesn't end quickly, the Dragon will become more and more likely to win, I think.

So I would guess maybe 60-40 to the alligator.