The car is a 1965 barracuda. The engine is a 73 do not know what it is out of. It has Clifford headers with offenhouser intake with 600 holley.The engine has nothing else done to it as far as know. It has rod linkage
600 Holley what? Vacuum secondary, Double pumper? A 4160 based VS model should't over carburete if tuned properly, You've got a 290cfm 2bbl already, even if the
secondaries never open so what? If You want, it's easy to disable the secondaries so they don't try to open at all, run on the primaries, tune, & go w/o all this switch/
swappin'/adaptin'. You didn't disclose exactly why You want to swap out carbs, so lets have it, running poorly,poor mileage, just think You should,.....?