Carburetor upgrade/swap vacuum connections

[dmjlambert]

I am a carburetor newbie, and you may have seen my posts in previous days about the trouble I had with working on my old carburetor.

I have a 1969 CST/10 with 350 CI engine, and HEI distributor from an early 80's Chevy truck, and a TH400 transmission. I have a vacuum tree on the intake manifold with 2 ports on it, and I understand those are for the vacuum canister and the transmission.

I ordered a re-manufactured carburetor from National Carburetor. I told them what truck I have, and told them I would like an electric choke upgrade. The salesman said the carburetor with electric choke is a different carburetor because they can't swap out just the choke part, but he said they could outfit the electric choke carburetor with older-style linkages so it would work on my truck. I received the carburetor today and I am excited at the prospects of connecting it and getting my truck going.

Pictures below.

Old carburetor vacuum connections:
d1 to distributor
d2 (under fuel inlet) to PCV valve
d3 to air cleaner snorkel switch

New carburetor vacuum connections:
n1
n2
n3
n4
n5
n6
n7 this one is threaded but not sure what thread dimensions are, I was not able to figure out with a thread checker. A 1/2-20 thread checker will screw into it 2.5 turns before stopping. A slightly bigger picture of that port is below.

I don't know where to connect the distributor, PCV valve, and air cleaner snorkel switch on this new carburetor. Can you guys help? How do I plug or properly connect to n7?