The low spot you're showing is where the fender cap is set up for a lap joint. I have always cut that section off and done a butt weld.
Have a look at the inside of your fender to see how far the rust goes. In any of my body work I use as little of the patch panels as I can.
In my experience I have always had to replace both parts that twin engines
linked to, but if the upper part of the mount for the headlight bucket is solid you can drill out the spot welds where the brow attaches.
I usually trim the patch panel down as shown in the fourth pic so the weld line on both sides curves up and over. If you have to change the bucket mount, cut the old one out, mount the bucket to the two holes in the fender and attach the new upper mount to the upper two holes in the bucket. This aligns it correctly and you can weld the two lower bits to the fender on the inside.
You'll need to use the headlight trim to check the fit to the cap.
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