Engine is a 1957 chrysler 392 with a Dyers 6-71 blower.Carbs are double pump Venom II 780.Engine runs fine except very rich.Fouling plugs.Don't know what jets are in because everything is new.What procedure would you tuners use.How would you check vacuum on each carb?Cab,are you out there?Thanks in advance.

I don't know those carbs at all so I can't tell you exactly how to fix the rich idle and part throttle mixtures other than lean the idle screws down as much as possible and go from their.
As far as measuring the vacuum on each carb I have one of the old carb synch devises that sit over the top of the carbs and have a visual indicator to use on the idle vacuum, I haven't used them in years
I tune them, multiple carbs, by ear and smell

The first thing to do is get the carbs apart and pin every single hole in it. On both carbs. Then you can start thinking about what the carb needs for a tune up. If it’s rich at idle you may have to reduce the size of the idle feed restriction. And it should be moved from the upper position to the lower position if it’s not in the low position already.

You can’t make any competent tuning decisions until you know what you have. Once you do that you can tune from there.