What would you do?

Okay... the rear floor and inner fenderwells are getting cut out for my backhalf kit soon... thereby providing lots of easy access to the back side of most of the sheetmetal, so I thought it would be a good time to do some badly needed bodywork. In the attached photo you can see the result of someones very poor attempt to fix the front section of the rear quarter panel. This was filled in with about an inch of bodyfiller when I bought the car, but you could see there were issues...
So, I can try to fix this several different ways. I refuse to take this to anyone else for repair, I insist on doing it myself, but I do have some experience in metalshaping and finishing. A replacement quarter panel is not available. (Valiant 2 door post, not a Dart)
1. I have body hammers, a stud gun, a slide hammer and a lot of patience....
2. Or I could simply cut out the damaged area, straighten and metalfinish it on the bench and weld it back in...
3. Or I could cut the similarly shaped piece from the rear door of another Valiant and weld that in.
Or...???

What would you do?

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