I've got a FW (4 speed wide range) with a post war Cyclo 2 speed conversion block, gives a range of 6 nearly equally spaced gears, one close and the remaining gear is repetitive.
Have of yet finished the build ( oh the shame of it) so I can not comment on actual outcome, but such conversion were common place in post war England. See:
Hybrid Hub/Derailleur Gears for more details.