If I ever saw and engine that could use a dual Holley 4v set up it is the Cleveland.
The engine loves a 600 cfm on the bottom end and it can use the huge breathing with a progressive kick in that dual 600 vacuum seconday carbs provide.
I have that set up on my 68 GT350 with it's stock looking 302 but with it's 347 innards.
The thing screams and gives 600 Holley mileage at around 18.
The only way you could do this now is with a Wieand tunnel ram and 1" open spacers under each carb, like what Marlin Jack has done, since there is no dual 4 manifold ever made for production. Only a few for Ford internal experimentation.
You will get some of the throttle progression with it, but not all of it and you will loose the fuel mileage benefit of running on just one Holley 600 (list 1850) carb.
A 650 vacuum secondary Holley is probably the best compromise although I hate to tell you to experiment but a 600 double pumper Holley surely is very responsive on this engine.
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