M21 Rear wheel

[Hobbs]

Afternoon all.
        My 1958 rigid M21 has the non QD type rear wheel and the sprocket is beyond redemption.
The brake drum/sprocket is attached to the hub with rivets and I don't believe the drum/sprocket is not available as a replacement part. For that matter I have yet to find the complete hub assembly available either.
I have heard that it's possible to have the sprocket either re-toothed or machined off and a new sprocket welded on.
Has anyone had experience of this or may know where I can get this done or who can do It.

Best regards.
Hobbs