The GOAL with the overlap is to blend it with a SKIM coat of filler. We shall see how well that turns out. I attempted to butt weld a skin on my '66 Chevelle a few years ago and between the mis-match of shape, heat expansion, weld shrink, etc., it didn't go well. Then I tried flanging the seam and that distorted the curvature of the panel. With this method I have had decent success with controlling all that to a minimum.
The plan is to spot weld the trunk drop and then fit the outer wheel house patches and weld/spot weld them in.
The right side gets a full quarter, so should be a lot easier.