I recently bought a challenging project. I am not sure it will ever shine again. The tank/fount is steel, and the lamp was very rusty in all parts. I gave it a bath in diesel for a week and then I could disassemble everything. The mixing chamber is missing - I would love a photo of it, to start searching for one. So far I have cleaned the tank on the outside. Much work ahead.
Well done for removing such heavy rusting. It must have been a lot of work on that alone. Perhaps this thread might give you some ideas:- First Hasag 351L
Rough but they are sturdy lanterns. Do you have the upper part of the burner: the J-tube? If so you can fit any burner with the right diameter for a 350-400cp lantern. The lower part is thread on the J-tube and a brass burner holder and finally the ceramic burner itself. Or a steel version with mesh.
I used "brute force" - rotating flap sanding disk :-) and later applied penetrating oil to stop rust in the 'pits' of the tank.
Thanks @WimVe . Yes, I have the J-tube. The old brass burner holder is broken in the threads of the J-tube, so it will take some careful work to remove it. But it should work. Thanks for the tip!