The work in the second of your pictures is very likely the same sort as what I observed after the fact in the creation of one type of 'hand-built' estates (station wagons) in England as in a 1957 Ford Consul (4 cylinder) where most of the existing roof was essentially retained, and a new section fitted in and of course brazed in and seams lead filled etc. I was shepherding the process with the local mechanical/body man on the rebuild of one locally--I had contacts in Malta, Britain, Australia and New Zealand for NOS or repro bits of chrome, stainless, plastic and rubber etc. The English factory at the time did not do wagons or convertibles directly, and those--although factory offered--were all hand built at outside coachworks.
The senior English Fords in the same line--the straight 6 Zephyrs and Zodiacs--had more of the real treatment as in the top 49 Kaiser wagon photo, where the rear doors and C pillars were changed and instead of an 'add-on', it was a new roof entirely. Most of those, also as ambulances, were done after manufacture when the cars arrived in New Zealand or Australia. Down Under, they seemed to do a much better job of it esthetically than the British coachworks, (although the British work was excellent in quality) Much more 'seemless' and 'seemly' LOL!
Frankly, I don't really miss not having Kaiser wagons, because we would never have had the doomed early experiment of the Utility cars otherwise. The sad thing for me is that no real efforts were made to create a 'halo car' 2 door convertible in the second series Kaisers. A cheaper entry-up-to-luxury level convertible could have likely paved the way for enough sales to have made the supercharged 54s and the Darrin less of an odd last gasp and more mainstream.