ScaleMode.ScaleAndCrop Crop Direction

I have a uniquely shaped health progress bar that I need to crop off the top as the health goes down (code below). I'm using ScaleMode.ScaleAndCrop, but when I make the size of the texture smaller, the image is cropped from both the top and the bottom. Is there any way to crop only off the top?

GUI.BeginGroup (new Rect (0, Screen.height -300, 200, 300) );
GUI.DrawTexture(new Rect (0, 300-(health), 200, health), bagFull, ScaleMode.ScaleAndCrop);
GUI.EndGroup ();

If I understand what you're going for correctly, it sounds like you can draw the whole texture, and let the group do the clipping, e.g.

GUI.BeginGroup (new Rect (0, Screen.height-health, 200, health) );
GUI.DrawTexture(new Rect (0, health-300, 200, 300), bagFull, ScaleMode.ScaleToFit);
GUI.EndGroup ();