I am not a tuning expert, others here have been a helpful resource in my efforts.
As a starting point, the hat that you have will provide a good measure between the carbs, the other hat that you mentioned (picture below) that is available will enable you to make sure that the barrels within the carb are synchronized.
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For example, the throttle butterflies should be adjusted to ensure that one side is not uncovering the progression holes more than the other at idle. This could be due to linkage tension or the adjustment at the screw that is on the progressive cams (arrow shown in the picture below).
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@Stevehose mentioned in my thread (
link) "Have you checked the flow on the secondary barrels? They should be flowing <.5 or so at idle." In the 38/38 there is really no secondary (as I understand it) as both barrels are opened simultaneously, but I will also admit that I still have a lot to learn.