if they are not blower carbs to begin with you will need to send them off to BDS.Mert Littlfield or someone like that and have them blueprinted for a roots blower..
if they are blower carbs i would adjust like any other carb, which will include plug readings etc...
i personally prefer EGT Pyrometers for blower applications..due to the amount of air moved thru the blower...this is a sure fire way to see how lean or fat you are, without having to WOT ,killing it and checking plugs etc...
This is how i had all my blown motors set up ..alcohol and gas. inj and carb
Brian
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Bjuice..
"I'M YOUR HUCKLEBERRY ! "