I have an '86 berlinetta that I just put a 350 in. I have a Holley 750 cfm with mechanical secondaries and there is no port on the carburetor where there is vacuum only under engine load. Is there anyway I could add one to the carb or do I have any other options to hook up the vacuum advance on my distributor. Thanks.

It should have such a port. Should be in the passengers side of the primary metering block..above the mixture screw.