This is what the Sunnen cone looks like. You just stick it in there and move it up and down until you have it perfect. You will have it marked with a magic marker. Just sand to the line you have marked. It's going to be harder in the car with the pistons in. You will have to move the piston to the bottom and stuff some rags in the bore to keep the grit out. Don't get in a hurry. Take your time and don't get any grit in your engine.