Thanks. A little nerve racking. Before I started this car, I've done some minor metal work but I'm still very much a novice. This area was one I hoped to avoid since I want to door to actually open and close properly afterward. Haha.
I ordered the other hinge pillar panel tonight so I'm gonna take you're advice and bond/weld them together first and install them as an assembly. The area I'm a bit unsure about is how much metal removal I need to do for install. Unless I have to, I really don't want to remove the upper cowl, the corner piece or the areas around the A pillar. Tomorrow, I will spend some time carefully removing the remnants away and cleaning so I can plan it out better.
If I can get this area right, it will really give me the confidence to do the rear of the car once the front end is done.