Brake indecisiveness

I get to ride a few different Nortons and the one with brakes that stop you  is a std SLS Dommy . It has shoes re-lined by a guy from france who turns up at shows .  Thats no help at all is it!.

Hi Tim, The best twin leader in my opinion is the Triumph one. That being the one before the conical. There are two variants of backing plates, go for the one where the cable runs alongside the fork leg rather than the one with the big loop from the backing plate.
You will need to measure the width of the Norton shoes  against the width of the Triumph shoes. Divide the difference and then slice this amount of either side of the Triumph shoes ( the Triumph shoes are wider). A band saw with a guide clamped at each end will work.
You will have to sleeve the hole in the backing plate where the axle goes. Then you will have to manufacture a stop for the backing plate to Norton slider. I'm thinking of a " T " shaped piece of aluminium so it will accept two button hole bolts drilled and tapped through the top part of the " T "and into the Triumph backing plate. Thus turning the anchor point on the backing plate from female to male. As your life may depend on it the anchor needs to be a very close fit into the backing plate and the aluminium of aircraft grade.
As the shoes are self centring they will take a bit of running in so the brake may disappoint at first. I am part the way there building one. Too many projects not enough time !!! good luck.
PS you will probably have to fit a spacer between the Norton bearing boss and the backing plate.

There seems to be some luck involved in the sense that different linings are so different in effectiveness, and the drum material probably has an effect.  My Norton TLS is very effective and has been complemented by a surprised MOT inspector.  I used to find the instructions to set up using two spanners was awkward. So I adjusted it off the bike by altering the length of the tie rod until both shows were just starting to be lifted by their cams at exactly the same moment.  Then fit the wheel, grip the lever hard, and tighten the spindle.  It only needs doing once with new shoes, and they should then wear in evenly.  A big chamfer on the leading edges reduces snatch.
The drawback with mine is that it can snatch violently when first used from cold if it's been left unused for two long in a cold shed.  I have to ride off slowly in a perfectly straight line with the brake held on until it stops squeaking.
Nobody much discusses extending the length of the actuator lever on the backplate.  PO did this on one of my Singles. It should be an easy way to increase brake shoe pressure on the drum.

Yes, a longer drum lever helps, I have one on the 99, made in stainless and from one of our suppliers, Will most likely need a longer cable which you will have to make . 

Most people don't recommend the TLS brake plate where the levers are pulled towards each other by the cable.

... to have a 7/8" pivot distance on the handlebar lever.

there is a longer operating now lever available for Norton TLS.

..
 from Norvil, 5.5 inch rather than 4.5 inch , between centres.