Cross referancing a 12V Generator for a 39 Chief

[48Chief]

I am doing a frame off restoration on a 39 Chief and am in the reassembly process.

Currently the bike has an obnioxious 12V generator of unknown origin and I would like to find a substitute with the approximate cylindrical shape as the original for use in the original style brackets.

Can anyone cross referance a modern 12V Generator for this application?

Thanks

[Kojack]

I hear that Bosch gererators like used on VW beetles and Opels will fit and have a similar appearance but I never tried one.