The exhaust is in a really bad shape. It has surface dirt and rust on it.
The battery has been leaking sometime in the past, a couple of decades ago, and it has left white marks on the engine mounts, exhaust, kick, battery tray and other things in it’s way.
The kick and exhaust.
The leak on the engine mounts and other parts.
Same surface dirt on the manifold.
The complete removed exhaust, I dont know if it is possible to clean out and reuse. There is no fracture or part missing, just dirt and rust.
Lambretta TV175 Series 3 
To me it looks like its in good condition. Never let yourself be foled by a thin layer of rust or dirt. Using a brush and some good kemicals it will probably be in very decent condition. My experience is that its much better to use old orignal parts if possible then repro, unless you build a custom scooter and want more finish then funciton.
I agree
I also did a “U” cut in my old exhaust, I cleaned it inside and then welded and, painted it
It works better then ever 🙂