when I cut mine out I used a cutting wheel on a four and a half inch grinder in cut just inside the tire well just below spot welds. I had a friend of mine make this temporary one until I was able to come across a good tire well.
then when I found a donor, I cut on the outside of the spot welds on the top. plus I needed that extra little section so that was cut also.by leaving the original spot welds and the addition of the new cut section stiffen the area.
Now just waiting to weld in place