looks to me like you have the 2 bbl bolt to the manifold throttle cable bracket on now. When switching over to a 4 bbl with the higher rise manifolds you need the 4 bbl bolt to the manifold throttle cable bracket as it sits higher and is about 1" more forward too.
So I would say you have the wrong throttle cable bracket on now sitting to low and too far back making it throw off the cable geometry to the 4 bbl carb and kickdown linkage, not giving it the proper stroke.
