Work on one circuit of the carb. at a time I would use the metering rods upper step to control the part throttle mixtures, get it right and then work on using the rear jets to get the wide open miture perfect I would try using a pair of two inch spacer under the carbs to increase the plenum volume and help make the motor more responcieve(SP?) to the throttle I'm not sure if the four hole spacer on the open two inch spacers would work better Using the two throttles hook together on a one to one ratio works way better on those stock type single plane dual quad intakes than trying to use them progressively like the later model dual plane intakes like the 426 Street Hemi intakes. I use to have a Chrysler 1955 331 Hemi in a 1934 Ford truck that I put a stock cast iron dual quad intake like yours on it, it didn't work worth a hoot with the AFB carbs hooked up progressively Same thing on my 1957 Chrysler 300C with the stock WCFB carbs., not worth a hoot hooked up stock IHTHs