The large nipple on the petcock is the fuel feed. It connects to the similarly large nipple in the middle of the carb bank.
The small nipple on the petcock is the vacuum line. You can connect it to any of the vacuum nipples on the carbs (each carb has a nipple, 3 of which are supposed to be plugged by caps.) From the photos posted you are missing one of the caps. Don't try to run the carbs that way.
BTW, since you are running pods you need to rejet the carbs. I won't even bother trying to start the bike until this is done since the bike won't run for crap. And speaking of pods, you should crack open the piggy bank and purchase some quality filters like those from K&N, APE, or UNI. The cheap generic cheapy pods like Emgo's are junk.