This looks like a really great repair.

I saw a video of rust around this area on a RHD car, and the Youtuber (I like his channel) is afraid this area on his car (not saying the OP's rust is as bad as the case in the video) might be structural and therefore it is unsafe to repair. He is not a W123 specialist or anything so I would be curious to read opinions on that from people on this forum:

https://www.youtube.com/watch?v=d5S6bCaKeLA