I’d probably avoid sending it straight to Longines before checking with a specialist who knows these vintage chronographs. The inner bezel may be the hardest part to source, and you’ll want someone who can confirm the correct original specification rather than fitting a generic replacement. For the case, light refinishing is worth considering, but I’d be very careful about over-polishing the edges. A good vintage Longines specialist should be able to source period-correct parts and overhaul the movement properly.
