Linkage was tricky but you just have to be creative and stick with it. Because both carbs have idle circuits it’s best to synchronize the carbs at idle. I have always used a uni-syn model A on my multi carb set up that used single bbl. carbs. Uni-syn also made a model 4B for carter and Rochester 4 bbl carbs. I have tried to get my hands on one but no dice as they are a little bit hard to come by so I used a moroso carb hat, drilled a hole in it and glued a model A uni-sun and then synchronized the carbs.
