The vacuum line to the transmission is usually connected to a vacuum port on the intake manifold, if you are running a PCV valve, it can go to the intake manifold also, or to the base of the carb on the back side...if it has a port there....

For rich at idle, adjust the idle mixture screws.. On your holley, they are on either side of the metering block (the piece between the float bowl and the carb body) start with the turned out 1 1/2 turns, then adjust for the maximum vacuum (if you have a vacuum gage), or til the engine is idleing smoothly.....