[Oldsguy]

Can't address all your questions but the choke tube goes to a hole in the manifold which goes to a plenum under the carb which is open to exhaust ports in the middle cylinders. If you have a different carb on there w/o choke tube I don't think it would make that much of an adverse effect as long as all the manifold vaccum openings are being used or else plugge up (and the choke is working some way or other ie, electric). I think you were asking if the opening for the choke tube goes to manifold vaccum, no it doesn't.