Leica I/IId conversion repair tips

Hello,

I recently bought an old (1930) Leica I converted II. Despite a good cosmetic
condition, and a "working" rangefinder (mirror needs to be replaced for contrast),
the shutter mechanism is almost missing.

I'm wondering what kind of part I could buy to get parts for this one. Does
all the Leica II share the same peices. Does some russian cameras have pieces
that are interchangeable with the leica II (shutter drum, speed dials, springs, ...) ?

Are some Leica III parts also usable on a I/IId conversion ?

Thanks you very much for any information

Richard.