Hello Spacke2speed,
I am emailing with C Henn about brake drums. He has one and your info about the two types has helped me understand what I want. It looks like my drum is the outside curved.

I have the complete speedmeter and drive shaft but it appears to be bound up and I hear a clunk when I turn the indicator over. I will take a few pictures soon.

The Magneto I have does not have a generator. I think it was broken long ago and was replaced. I will be on the lookout for mag/gen when I get the bike running.

Once I get the brakes working I will investigate the electrical system and post my findings. Most of the parts appear to be there and should not take too much to get it all working.
I think I will have to reinvent the wire. Conductor inside metal spring with something for an insulator.