I had a twin leading shoe front brake on my first Commando, which was not good!
I fitted a back plate (known as a stiffening kit on Norvils site) and had special "green ferodo" (I think) shoes machined to my drum size, which was only a slight improvement with the performance being mediocre when warmed up or hot. Also, on a morning, the first touch of the brakes nearly locked up the front wheel momentarily! I then fitted a Norvil racing disc with an AP caliper with a standard master cylinder which was definitely a better more consistent brake.
I'm talking about 25 years ago and my engineering/mechanical skills were very poor then, not that they are that good even now, but maybe it is possible to get a drum brake to be good, but I couldn't achieve it then. Having said that I have never had a totally standard Norton front disc brake set up on my Norton to compare. All my disc braked Nortons have had modifications made to them.