Make sure you have a good fuel pump and fuel line, old ones can restrict flow. Also you should make sure the carbs are set up properly, floats set at correct level etc.
Also as I mentioned, get a vacuum gauge, connect to your intake manifold and set your mixture, timing etc to highest vacuum, it's a great tool and inexpensive.
Be sure to look down the bore of the carbs and get the linkage set so the throttle plates open exactly together, then you can set mixture etc.
