Nivram, I don't actually use a gouge or anything to make the molding concave. My go to tool is a dogleg rat tail file. The dogleg is near the handle to provide finger clearance. I'm right handed so I usually use it with the handle in my right hand and my left hand is on the body of the file using my fingers to guide it along the ramrod channel. Removing the thimbles is not necessary, but I usually do. Once you have a basic groove laid out, you can wrap the file in sandpaper for finishing and enlarging the concave groove. I usually relieve the forestock down to the molding. All you need to do is draw a line down the forestock that is 1/3 of the way down from the top edge of the forestock. You can also lay it out from the widest part of the nose cap. From that line you can use a fairly wide flat chisel to remove some wood down to the incised line. 1/16th of an inch is all you really need to remove to make the molding stand out.
Dave