What about the setting on the outbiard idle mixture screws? Are the lead plugs removed so you can adjust and if so, what are they adj to? Also, are you sure the butterflies are all really closed? Have you looked down the carbs at idle and confirmed they are not being held slightly open by wrong gaskets, etc.. and the linkage for the outboards to the center carb...is it incorrectly adjusted, posdibly holding oitboards open? ( although now that i think about that, the slot in the center linkage arm might not allow it to do that. Let us know what you find.

I believe your jetting is in the ballpark. I tjink stock was 62 or 63 center. And outer metering plate orifices were around .083”-086” or so.