Hi Jan, I've emailed you a pic of the speedo bracket from the parts book. Feel free to post it here, sorry I don't know how to do that myself.
From original photos of bikes in ww2 the bracket appears to fit between the top headlamp bracket lugs on the forks.
Not sure if the same bracket was used on other makes of bike, I assumed it was specific to early W/NG.
Regards and thanks.