Here is how I adjust carburetor on my chevy.
Set RPM to 800 RPM
Set timing to 12degrees advanced(that is for my truck)
with the vacuum advance disconnected and plugged.
Re attach the vacuum lines.
Then start adjusting the carburetor by screwing the mixture screws in one at a time until you can see the RPM drop 50 to 100 RPM. This makes the mixture "lean". Now adjust the mixture screws out until you achieve the highest RPM as you can for each of the two mixture screws. By this time the engine will be running too high an RPM so adjust the idle speed screw until you achieve the 800 RPM.
I think this will do the trick