Study this pic.
Note that in addition to being leaned forwards, the pillar is also wider than it was. I did this to allow the window opening and the door opening to each end up where they needed to be. With the bottom curve of the window opening cut to angle the window forwards, and the door opening angling forwards the same angle, the pillar HAS to get wider. Right down the middle in the pic is the filler piece I made up, it just sits in the back side and the pillar parts are welded to it. Yes, it's lap welds, but there will be more weld remaining after grinding, and I plan to level these out with fibreglass filler.
The upper window frame was then relocated back to get the window opening to fit, and a small gap up top, where the filler is widest, shows how much it went back. Also note the upper curve in the doorframe needs to go back to mate with the pillar at the top, and then I will put in a filler panel up there at the forward cut line.
When I did the chop I shaved the drip rail first, then cut it loose along the back window above the frame. The lower part of the window frame wraps gfrom one quarter to the other, with the panels just set to the glass lip and tacked. I will still be able to reuse the greenhouse lower trim pieces this way. After removing the roof skin, I treated each post individually, starting with chopping both A-pillars and working back. After all were done the roof skin went back on, I trimmed the rear sides to fit down lower against the upper quarter window frames, then tacked the panel back on and started making up the fillers for the rear glass area.
A straightedge is a big help when reworking the upper roof curve to flow down nicely into the new rear filler pieces. That, and a lot of big chunks of cardboard to make patterns.
Doc