I just saved a driver side lower. Not sure if the whole thing was good in the area behind the fender or I was just saving it for the rolled shape where it meets the rocker in the jamb. But my most recent experience in shipping a batch of parts from US to NS didn't go so well. Not only was it triple the shipping cost of anywhere I could have sent it in continental US to get it into Canada, but then it sat in Customs for weeks, assuming it was quarantined. Then he said he had to pay an additional $60. I had thought the absurd shipping price covered the customs fees, but apparently not. The package was insured for his full purchase price plus shipping in case it did get lost and we thought it may have when it got stalled. But it did show up and turned out to cost him so much more than it should have. At least it was hard to find parts and not something that would have been easy to source from within your country.
The side where it overlaps the rocker shouldn't be too bad to just hammer shape steel over wood forms. So what if you don't also hammer out the triangle shape back at the door jamb roll. But you could with a recess cut into the wood block, by hammering a socket extension onto the steel and pushing it into the recess. It's labor intensive but I've done that type of work many times before having proper tools.
For the jamb roll itself, I had nothing for the rear jamb and sourced one from a late model back a few years ago. It would be the same concept. I made a carboard template of the shape as it rolled in, and just kept trying it to different cars in the yard until I found one close enough that I could force it the rest of the way. Welded it in and connected it to the rest of what I'd made. I couldn't do the exterior of my quarter panel at the time so painted it to hold for a while. But I couldn't cut the exterior of the quarter off either, until I had the jamb solid again and Something was holding it all to the rocker. I actually filled the metal folds where they remained with weld right to the late model flat steel face I had. Then finished their lower sections back in with Bondo to complete the look. It's functional and even though it wasn't perfect at the time, it got the job done so the next step could begin later. Here's a pic of trial fitting, and also of the finish at that time.
You can probably do this for less than the cost of shipping alone, if you were getting parts from USA right now.