Is it your reading comprehension or your mental agility that is going ??
If it turns 40 on 1st Jan, then its a 1973.
This is a COMMANDO list, so its possibly a Commando.
Nortons didn't make much else in 73.
If its 1973, then its either an 850 or a 750, disk braked.
An 850 strictly wouldn't be quite 40 yet, so its a 750 (?).
They were all the same 750 and 850, mechanically, about then anyway..
You'll have to excuse JAW, he doesn't actually own a Commando, just lurks here.
Sorry can't help much though with new rims, mine are still good.
Central Wheel is sometimes mentioned,
http://www.central-wheel.co.uk/
Andover Norton also has all things Commando, and then some.
http://www.andover-norton.co.uk/
stainless sound like the go, but haven't tried them.
Stainless rims also come from India, but the reports aren't so good ??
P.S. We see that Andover Norton are moving - to Andover !
Makes sense.....