I'd be interested to see what the air bleed changes are worth. I raced my car 8 years with a pair if 1407s. There was definitely an issue leaving off the foot brake even at 3000 rpm. Getting ready to run these carbs on my sons racecar. I've opened up the secondary well feeds. Tried heavy/light air doors. Various squirters. Raised the float levels. Run the idle fat. Never messed with the idle restrictions or bleeds. Never messed with the transfer slot location. At times we ran quick. But not near as consistent as the Holley's.
Doug