If you don't need a full quarter, don't do it. Just do a lower patch. The more original sheet metal, the better. If you do a full quarter, take your time, and don't go into the door opening. I stayed two or three inches out of the door opening, and didnt go over the top edge of the body. I stayed down in the first body line, which is the top body line that is approximately 1 3/4" and gets narrower into the door opening. There is some work involved filling the weld flanges, and warpage. I didn't do the welding on mine, but I am finishing the body/filler work, and it is teidious and requires patience. My advice is, be patient, and don't let anything pass as finished if you know/feel it isn't perfect or up to your standards.