Good deal on holley sending you the new metering plate, its always been hit and miss on the idle restrictors. Whoever is helping you is right, center needs more fuel to get to 1 turn out on the idle screws with proper air fuel reading. You may also need smaller main jets after doing that. If you look up the venturi size of the center and use a double pumper front plate that matches that venturi,600 or 650 I think, that works too and most old double pumpers have idle jets down low where you can drill them.