Yes, it certainly has BD.
Sadly I would call this leaning towards severe. To me this appears to be the type
where the entire body is susceptible. It must be a combination of bad alloy
- possibly high sulphur content copper - combined with bad environmental situation during its buried life.
The result is that the whole body might be dodgy with a crisp surface clinging stubbornly.
Can you remove the BD dust with a soft toothbrush without flaking away the surface??
If so, remove as much powder as you safely can.
I would consider waxing it. First baking it in the oven at low heat to remove remaining moisture, then, while still
warm, applying a thin layer of Renwax.
If you are lucky it will seal out moisture and there will be no self-generating moisture-induced BD under the wax. Also the wax might help
protect the flaking.
Worst case, the BD re-appears under the wax in which case you need to strip it off.