X2. If its not ported and your looking for more power, get that done first. I still run stock carbs on my Wildcard Racing aggressive dune ported 350, and the thing rips so damn hard. I'm sure carbs would help, but It runs great right now with stockers Yeah every little bit helps, but I think you'll see bigger power gains having it ported first.
Not 100% sure, but I've been told stock carbs will handle up too about 65-70HP.