73 quarter panel replace

[AmadeusCharger500]

Picked up skins for both sides at Carlisle. Both are a complete mess from the wheel well down. I will be cutting the car an inch or 2 from the top body line. Im concerned about fitment and what to do at the door jam area. If i cut an inch away from it how do I measure this on the replacement. Was thinking of just leaving the side marker light on and cutting around it just to make sure the skin is fitted. Any pointers?