You can tell if the alignment rings contributed to your problem once you remove the manifold. They will either be deformed, or you won't be able to bottom them out in the block or the manifold (due to debris).
A better way to check for a vacuum leak is with an UNLIT propane torch. Turn on the gas a bit and move it around and listen for an increase in RPM. To get a feel for what you are listening for, move the torch near the carburetor so the propane goes in and increases the RPM.
Carl

Last edited by 52Carl; 08/16/2015 2:46 AM.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission