I converted my stock 318 2bbl to a holley 600 cfm universal. Vaccum secondaries, electric choke.

I got a 340 4 bbl Single air cleaner off of a
later model car, so it retains the heated air cleaner. I got the 4bbl throttle linkage off of
a 78 4bbl Diplomat (I think)...

The car starts and runs beautifully.
In fact, the vacuum is up almost 1" hg because
the air horn isnt warped on the new holley.

I used an old MP P4529116 aluminum intake.
Felpro gaskets and I closed off the heat riser
ports.

Like I said starts and runs with no problems.
The biggest boost that I get is at highway speeds
when I want to pass somebody...
I get a nice pick me up there...

Otherwise there isn't much difference vs.
the 2 bbl carter.

The idle speed is the same (700 rpm) with automatic (904)...

I run factory A/C.

Even after the car is started cold (and exits fast idle) with the AC on full blast
car idling in park with headlights on, blower motor on,,, car idles nice and smooth.
just like it did with the 2bbl...

The engine setup is stock though...
no change in heads/camshaft/.
its a 318 block bored .030 over...

Having done this upgrade recently,
I wished I did it 10 years ago....

Hope this helps...