Roger, as Internet John points out, there are very few from the 2 stroke group of members who contribute to our club's forum.
If you are on both forum's, maybe you could have a word? You might be able to at least find out what the problem is. This forum was deliberately set up to equally support the smokers.
Many of the things that are applicable to Leaders and Arrow's are just as useful for the four strokes - like creating a twin leading shoe brake.
I expect your best hope is to upload a couple of photo's or a diagram that shows what you are looking to achieve - or at least the basics of how.
Do you still have the back issues of Cheval with the brake of interest?
I'm not sure where you are from in the UK - near Silverstone? Someone local to you may know a good engineering firm, or have the skills to help you out.
Are you building for a road racing or street bike? If for racing, you can use anything pre '62. From memory, the two strokes had reasonable brakes - you may well get a better result by having the drum and the linings skimmed (just open) round.
This was interesting http://www.realclassic.co.uk/techfiles/ ... 00900.html http://www.voc.uk.com/net/docs/2.1/2.1-192-12.pdf
With minimal work, this might do the job - for you, and John. http://www.hitchcocksmotorcycles.com/ac ... ame-brakes
Twin hubs sounds great - like a Vincent! - but the unsprung weight...
51 Square, 48 VH, '27 Model C, R67/2, Mk IV Le Mans, and a couple of Ariel projects.