What Alternator Stator ?

Can't advise on new alternators. 

These are good regulator/rectifier boxes.

https://www.ebay.co.uk/itm/317112493018?mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338778191&toolid=10001&customid=130832X1595795Xd14bf1860384640515ca137e80f32af5&subId2=15

Plug and wires.

https://www.ebay.co.uk/itm/317112536052?mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338778191&toolid=10001&customid=130832X1595795X7f503c9c8f3b448b6ff978debd99bab4&subId2=15

Just ask Al. 
Oz that is... 

The original stator would have had a 70mm rotor (and stator to match) but this size rotor/stator or no longer available as new. So you are stuck with the later 74mm rotor stator, the basic item being the RM21. LED lights will reduce any demand for electricity, while indicators are intermittent usage (maybe even LED) so hence are not to worry about, With regard to rotors-these are magnetically /electrically all the same, but with age the rotor might be coming apart and its magnetism can reduce, can be tested (see my web site). Only other area of concern with regard to running indicators 'on all our bikes' is to make sure we have a decent battery, none of the 'gel' ones from the alarm world, but something with reasonable AHR ie you can get 7Ahr and even 9Ahr in a Dommie battery box.
With regard the reg/rect recommended by M Ball, we do NOT know if this is for permeant magnet rotors, and it is for 3 phase this is not for use on an RM21 (single phase) My advice is stay clear of this item unless you KNOW what it is for and how it is meant to be used. ie on specific Hondas

The generic Chinese "CBR600" reg/rec I linked to is in use by me on a permanent magnet, single phase alternator.  I've fitted and used a few. Many other old bike riders use them. They perform well and last well.  They show precise voltage control and don't get hot.

That's why I recommended it. I'm surprised Al Osborn doesn't know about them.

As my alternator is single phase, one of the reg/rec's yellow wires is not connected. Some people connect two yellow wires together to one of the alternator output wires.

It might even be worth an expert's time running a few tests on one.  After all, it's not a big investment at £11.53.

The early Indian Enfield Bullet stator would appear to be dimensionally correct. Try Hitchcock's for advice and supply.

If the tatty old stator is the type with exposed coils, it's a fair bet it would fail at some point.

Don't throw it away!

This is the colloquial name to the very 'square' cornered batteries that have 1/4 Luca terminals, they are made for the burglar and fire alarm world. They are meant to be float charged for a long time and have a lowish  limited charge rate (depends on the Ahr as to how much) If they ever get over charged for any length of time they will dry out and fail. They are not meant for Automotive use, which is highish short term charge/discharge. Our bikes were made for the Flooded acid type which when they overcharged (the earlier 6V) would tend to boil off, (you then topped them up). The gel type if they over charge dry out and fail-end of. AGM seem to be very good for our bikes.