Ime, the average cage driver is not looking, confirmed by firefighters over the years who, in the UK, are usually in big trucks painted bright red with both headlights and blue lights flashing and two different sirens sounding ...
The original Lucas company rated the standard 74 T150 RM21 alternator for 10.5A @ 5,000 rpm; however, also according to Lucas, it only produced 75% of that @ 2,400 rpm (< 8A) and the workshop manual test with a 1-Ohm resistor says 9A AC @ 3,000 rpm.
Also, this assumes good rotor magnetism; original rotor in your bike would be 48 years old ...
Ignition coils draw between 3A and 4A unless you use a Tri-Spark electronic ignition, but even they only cut the draw by about 0.5A.
Plus the ignition, standard headlamp 35W dip filament draws 3A, or a bit more if the bulb has been replaced with 50/40; standard tail lamp draws another 0.5A; good to have spare alternator capacity above total constant draw, to keep the battery charged after periods of very low rpm, using turn signals, horn, etc. 30W auxiliaries would draw 2.5A so, if the engine spends a long time below 4K rpm, you would only be able to use the auxiliaries or the headlamp, not all at the same time.
The UK has never had a lights on in daylight law and, until recently, I have never ridden with lights on in good visibility. However, because so many European countries do have the law, numbers of all vehicles with lights on all the time have been increasing for years by default, it has become increasingly difficult to spot a completely unlit vehicle, especially a bike, even in clear visibility.
Fwiw, I have long used a bright pilot bulb in bike headlamps in poor daytime visibility and under streetlights at night; ime, works well because it 'fills' the headlamp with light to other road users in front of the bike, but does not dazzle any one. Current bright pilot 'bulbs' are https://www.ebay.com/itm/284599576488;
one replaces the standard pilot bulb and holder, the LED's 23 mm diameter is bigger than the hole in the headlamp reflector, it is secured in the reflector by clamping it with the nut and a washer outside the reflector. I now use that in daytime as well.
If you have tried to find a LED replacement for the rear bulb, you will know it is difficult because the bulb hangs vertically, so most LED replacements would point the brightest LED at the licence plate instead of at the driver behind ...
However, I have recently found these
- I appreciate it is a British site but I am guessing there is similar in the US?
I hope not a long term plan; it will not do a triple engine (or a Triumph twin engine) any favours. If you are concerned about road speed, Hurricanes and some T150's were fitted with 18 tooth gearbox and 53 tooth rear wheel sprockets; does not do anything for top speed but would allow higher engine rpm for a given road speed. Gives a triple's clutch an easier time too.