I have a couple of GMS .47s in a twin that are now running fine.

-My GMSs took at least a half gallon to run smoothly. One of them took a gallon of fuel through it.
-Turn your low end needle out a half turn to make sure you don't have it so far in, the top end won't adjust, then try it.
-Don't worry about a good low idle until you have a lot more fuel through the engine.
-I had some trouble with the remote needle, so all mine, .47s and .32s, now have the front needle. You might try moving the needle to the front (I am assuming you bought the remote verstion) and giving this a try.
-Even if you don't move the needle, unscrew the whole needle valve assembly from the rear mount or the carb and blow out the area. I had some black gunk in mine and blamed the engine until I checked.
-Check your tank location. It should be vertically located where the center of the tank is even with, or a little lower than, the fuel jet in the carb. Having it lower than this will cause leaning out in the air.