Maybe this may help some at this time:viewtopic.php?f=1&t=679
1. Data is at 10" water. The airflow depends on the sy choke size of course not the carb barrel diameter.
2. You need to be careful with the ratio of choke dia to barrel. To get a decent fuel signal and if tuning for max power, typically do not exceed 85-88% ie: 40 carb 34mm choke, 45 carb 40mm choke, 48 carb 42mm choke. You can work out the ratios from that.