There’s a pic in here in post #11 of how an automatic choke works. It has a choke stove and linkage rod. Your intake doesn’t have that.
http://67-72chevytrucks.com/vboard/s...d.php?t=416118
The distributor vacuum line doesn’t control your choke. It’s for your vacuum advance.
You need to remove the choke pot on yours and plug that port.