Classic/Antique Car Repair: 1948 hudson, carbeurator, engine failure

Question
I have a vaccuum leak in the intake manifold of a recently rebuilt engine.  The mechanic doesn't think it that bad that it needs to be corrected.  My question is: are all vaccuum leaks serious enough to require attention?  The problem I am experiencing is the car will die whenever I come to a stop. The carbeurator has been rebuilt several times in an effort to correct it, no luck.  Several people have told me that the mechanic is wrong and that this problem MUST be fixed in order to eliminate it as a cause of engine failure.  He is reputable, I trust him, but everybody else I have spoken to think otherwise.  Any thoughts?

Answer
PAT ;
 HI - well a leak is a leak - and even if a little it is still a leak-what if it was  gas , it would be all over and than go BOOM right. I would just fix it and be done with it , if you can not tighten up the intake or where it is leaking from ,so I would just fix the leak.  ok I do not say that the mech. is wrong , it might not be that bad and you can still drive it ,but if it is causing the engine to stall - well thats bad to me.   ok