What is this?

I bought this Demon with a 6 cyl. It has a Holley 2 barrel on it and it runs, albeit not very well, but I'd like to correct that. I don't have a service
manual so I have a couple question?
What is this fitting on the intake...it doesn't look properly set up to me... what is it for? I'm missing PCV valve and the distributor advance is not hooked up, are these supposed to be routed to this as well? Do I even need this with the Holley set up?
Thanks

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