As strange as it appears, I have solved my running problems by replacing the Weber 32DFD carb body with a spare body I had. We assumed, after a long process of elimination, that it was possibly a clogged passageway in the carb. The carb in question had been the subject of a complete "professional" rebuild. When this saga began there were other issues that led us to inspect the carb. We found the venturies were loose, the accelerator pump valve was incomplete as it was missing the lead plug and ball, the float was improperly adjusted and the vent plugs that belonged in the cover were lying loose in the body. Once all these issues were rectified the car started easily and with the accelerator pump working it would not stall. Although the pulsating periods of rough running at between 4 and 5k RPM's continued. As this carb was vibratory cleaned and polished at time of rebuild I am wondering if the polishing media has migrated into a passageway. When time permits I will inspect it thoroughly.
It is good to have the engine running as it should. Thanks to all who offered advice.
Bob