Hello Francois. I think you can use the post war footrests and modify them. You can drill and tap the end for the washer and bolt. Others who have done it might have other information too? The early rubbers should be easy from Jeff Hunter. Ron
Years ago, when we had the web link to , From Birmingham to Berlin, which seem to dissapear. The two lads on there converted a set of flat footrests into the early one's. I used this for doing mine. I can't remember exactly what was done, the flat part was cut off and a round bar welded on, with a threaded end, like Ron mentioned. I got rubbers from Jeff, and the washers from Henk.
Many years ago I converted a post war footrest to make up a pair, they were hard to find even then, I just drilled and tapped the post war one, they are wider and slightly thinner but it still just fitted in the rubber but I probably should have reshaped it.