Carb fuel question and fitment

[AcMedic]

Bought a set of carbs from eBay that the seller assured me would fit my 79 CB750F SS. There is a "T" fitting along the fuel rail between #3 and #4 carbs. Should this be capped? Pics for clarity. Also, there's a capped nipple on the throat of #2 carb. Does this supply vacuum for the slides in my carbs? I know, rookie questions, but this is my first foray this deep into a 750. Thanks in advance!

 

[Sevencycle58]

Please talk to the guy at themotorcycleprojectcom.
He only works on Honda carbs. He is an expert in Honda carbs. He might chew you out for buying unknown carbs.
You said a '79. Your carbs should be VB42B. This will be stamped on Carb #1. That's the one on the left side.
The T fitting is a vacuum line. Gas is between #1-#2.