This section of door is the best out of all 4 parts that are going to be used. Had some small spots that I opened up with the die grinder until I could feel and see uniform thickness all the way around.
Cut out fill into pieces one gauge thicker than the door to give some sanding room afterwards.
Welded in.
Need to make a dolly to fit in the narrow space behind the patch so I could planish it. Could only find this scrap piece the right thickness.
A bit of shaping later and it fits well. Can slide it now down to the other end behind the patches.
Came out well enough, and most importantly, the little bit of distortion I had was removed.
The welded edge of the door jamb has been cleaned up and sits flush.
Gaps look better now.