going Commando...

I have little doubt that, roughly four decades after they first appeared, Commandos are performing better than they ever did.
Over that time-span there have been so many people involved, so many tests, so much development it is truly staggering.
All the special parts we take for granted today, and fit to our Commandos, are borne of a tenacious relentlessness on the part of those riders and engineers who understood that the Commando was always a remarkable motorcycle, but that it could be much, much more.
This pursuit of excellence was honed over the years, focused on those areas that mattered the most, whilst leaving the rest untouched.
We won't get into the "original vs. modified" argument here, I think both sides have merits, speed freaks and rivet counters alike. As with most things, I believe the sweet spot is somewhere in the middle.
To me, there is no point having a 100% original Commando if it means you won't be able to enjoy it as much as one with the relatively simple improvements and few parts listed below.
The same is true of the opposite: a 1007cc Maney engine, housed in an all-alluminium monocoque frame, full fairing, full kamikaze racing specs is no longer a Commando: it's a terrifying speed machine that will have no rivals on any race track in the world, but you will not be hopping onto one at the end of your night, after you've had a few and you're a little "tired".
I also don't see the point of any other capacity than 750cc, but that's to do with the Interstate I grew up lusting after. That said, I have ridden properly set-up 850s that were awesome, though I wouldn't go for one myself (same goes for electric start, 920s, 1007s, etc.).
The press of the time, '69 and the early 70s, sang praise of Norton's formidable new machine, fast, vibration-free, powerful, sophisticated!
Yet if you read those articles today it is clear how much progress has been made, in improving so many areas of the Commando:
ß The entire electrical and ignition system, for starters: today they can be made simpler, with fewer parts, whilst also being truly maintenance-free, more resistant to wear and humidity, and infinitely more reliable;
ß Suspension is greatly improved by something as simple as progressive springs for the front forks, and FAC or Asatek shocks at the rear;
ß A belt-drive primary conversion wins you back a few ponies, whilst eliminating oil from the chaincase and saving a substantial amount of weight (just over 2Kg if I'm not mistaken);
ß Vernier type Isolastics front and rear, coupled with either a Norvil or an Andover head steady mean easier installation, easier adjustment and a rock-steady quality to the overall ride that will have you pleasently surprised, time and again:  "This is a 40-year old motorcycle? And it handles like this???" Yeah it does...;
ß Brakes can be greatly improved, front and rear, with a myriad different things, drums and discs alike, from subtle to in-your-face.

Then there are things like the engine, carburetters, clutch and gearbox, that have always been damn-near perfect anyway.
Yes, you can upgrade all of those as well, but really the main benefit we have today as opposed to when they were new is that by now so much is known about them that gremlins have nowhere left to hide.
A hand-built (blueprinted, if you will) engine coming out of a competent mechanic's workshop today is likely to be better than an original engine trying to keep afloat during the dark ages that were the mid-80s.

Here's the recipe my Fastback was cooked to, in no particular order:

• Brass cage "Superblend" crank bearings (FAG NJ306-E-M1-C3) (Andover);
• Standard conrods, polished;
• Vernier type Isolastics (as for the head-steady below, these are available from several different sources, choose wisely...);
• Norvil head-steady (an actual Isolastic. Andover, Mick Hemmings, Norman White, Comstock and no doubt others have also developed their own version);
• Belt primary drive conversion (RGM);
• New crankcases, stronger  (064045 from Andover);
• Stellite valves;
• Titanium valve collars* (Norvil);
• 4S camshaft (Andover);
• Maney alluminium cylinder;
• New Amal Mk1 carburetters, 32mm with a few trick parts (Burlen);
• Boyer Bransden ignition and Powerbox;
• Braided stainless steel rocker oil feed pipe (065561ss from Andover);
• Stainless steel fastneres throughout, Allen bolts on engine and gearbox covers;
• K&N air filter (R-0990); 
• Lockhart oil cooler;
• Flanged alloy rims;
• Asatek rear shock absorbers;
• Tapered steering bearings (FAG 30205A);
• RGM/Novelli rearsets;
• Alloy front mudguard;
• Tommaselli headlamp brackets;
• Progressive springs, front forks (RGM);
• Fontana 250 brake.

You will often find many of the parts listed above from different suppliers, and whilst most are probably ok, for peace of mind I would only really go with Andover.

*Yes it's cool to say "titanium", but in retrospect I would not bother with these and just fit standard valve parts from Andover.