"cap it off hard"

If you have a 53/54 (or, earlier) BC, that choke uses a heat stove that is clamped to a manifold. It relies on heat transfer to actuate the choke flapper and it is "balanced" by engine vacuum. It literally sounds like you have a vacuum leak?

I'd "cap it off hard" - plug that leak.

Let's see what others have to say?

http://chevy.oldcarmanualproject.com/carb/Rochester/9C304p02.htm
http://chevy.oldcarmanualproject.com/carb/Rochester/9D8p07.htm

Tim
1954Advance-Design.com
1954 3106 Carryall Suburban
1954 3104 5-window pickup w/Hydra-Matic
The 216 and early 235 engines are not "splash oilers" -- this is a splash oiler.