One of the contributors to this board has some photos of work in progress on an oval window business coupe which is a lot like the sport coupe. The rear cardboard corners and top attach in the same way. The difference is between the oval windows and the landau bars. I think he has posted other photos on this board before.
http://www.model-a-ford.com/proj_3.shtml
It's interesting to note how the wires are attached that hold the inside edges of the cardboard corners. The straps that support the top fit into shallow reliefs in the bows. All this hidden support system is what holds everything in shape. The parts on the inside are wrapped with cloth to act as trim and as a headliner of sorts.
It truly is a soft top but it's just fixed unlike a cabriolet. It is really a pretty simple design but it's not necessarily easy to install. The kits make things a lot more simple than if a person fabricates everything but it can be done either way. Kits generally come with instructions. Volume 5 of the How To Restore series of books has a lot of info with photos and illustrations on the construction of these tops.
I found this link with B Terry's photos of a sport coupe in progress for those that haven't seen it.
https://www.fordbarn.com/forum/showt...port+coupe+top