Well I would hope they are only loosely based on the original, certainly if the original that I had some years ago was anything to go by!
It was a pretty awful thing. Consensus of opinion was that the choice of alloy for the hub was wrong. The thing expanded so much when hot it was impossible to deal with, I set it up dragging, but after 4 laps or so the lever would pull back to the bars and I had to adjust it whilst riding. Then, when cooled after the race the brake would be on pretty tight and need the adjusters backing off again!
I doubt this would ever surface as an issue with road use though to be fair.
Steko, I don’t think this 4ls brake was available in 1954, however it was certainly used on a number of period cafe racers over the years. I have one that I am going to use on my Ironhead Sportster engined Slimlne special.