I use a leak down for 2 things, get a starting point and finding out where i ended up at. That being said, I would start the car up and use the fuel shut off valve to lean it out until it reached operating temp. Then once you are at operating temp, put the lean out in normal run position. Now you need to shorten the linkage between the barrel valve and throttle linkage a couple of "flats". now you going to "wack" the throttle to see if the engine still responds. If it does then lean a couple more flats and repeat until it stumbles. once it stumbles add flats until it doesn't, then add two more flats and you are set. Now check your leak down for future reference. if at any time the idle gets to high, use the throttle blade to close the air gap. the idle screw is for idle speed, the barrel valve is to set the idle A/F ratio. DO NOT USE THE BARREL VALVE TO SET YOUR IDLE SPEED.

some notes, each engine has a different leak % due to pump size, idle check valve pressure and of course cam. i also have customers bring their own leak down gauge, they all read different.

one more thing, can you post a pic of your engine? mostly want to see where the fuel lines are running.