I didn't know that Imron was still being made!
You'll never take orange peel off by buffing. Have you ever heard of the terms "Cut and buff"? The CUT refers to sanding the paint/clear. The buff obviously means the buffer.
All is not lost. The surface needs to be sanded to where the high spots of the orange peel are sanded away and the surface is even. At that point, You buff with a rubbing compound followed by a polishing pad and compound. There are videos on YouTube. Good luck.