My 65 Nova has a early 283 Military intake with a WCFB carb pattern, the adapter that is on there has tapered hole, something like this , but to more of an extreme on the primary side , but leaving the secondary side open, or non tapered???
The adapter I have is like this.
http://www.55chevys.com/chevytalk/carbadaptor1.jpg
I am changing my intake out soon, so if you would like my adapter to play with let me know