If it will rev, it is unlikely to be the distributor plate shorting out. Your subsequent posts lead me to also believe that the carburetor is the problem. The sucking sound when the throttle is slowly opened leads me to believe that the float is set too low. Remove the carburetor top and look at the float. It should be level across the top. If it is not raise it and see how it runs.
But the vacuum does advance the timing when the throttle is opened. Ported vacuum is 0" at idle and increases when the throttle is opened. It will drop to near zero at WOT.But low RPM response is great improved with vacuum advance on light duty engines.