Hi Dee
GH flies are very much location specific. The ones that work well are SECRET. Pm me details of where you are seeing these fish, and I'll let you know which flies work best in that area. Of course, I'll have to test that the flies will work in that area.
In all seriousness, just about any baitfish profile fly will work. Just have to work out what mood they are in. Most times, they want the fly moving and moving fast. When they get moody, you'll need to waft the fly in front of them as long as possible to entice a bite. Match the size of bait around, and you should get some action. Being in the right place at the right time is the key.