Here you go:-
https://www.minispares.com/product/Clas ... o%20search
Currently out of stock but worth the wait for stock to be renewed.
Here is a damper pulley on 'e' bay. Looking beyond the bad paint job the rubber appears to be serviceable.
https://www.ebay.co.uk/itm/196187650132 ... R7yN0eujYw
A good grit blast and it should come up like new. Personally if I was looking for a damped pulley I would consider it worth a punt.
The crankshaft damper is one of the best things that you can fit to a 'A' Series especially the 1098cc engines.
They do come up for sale on 'e' bay but you have to make sure that the rubber is not coming apart.
I have had a crankshaft damper on all of my tuned engines and would not use a tuned engine without one.
The BMC/BL damper will have been balanced at the factory but any after market damper will need to be balanced as part of the rotating mass balance process to get the best out of it.
You should not fit and use a Cooper 'S' two piece damper unless it has been balanced as part of the rotating mass balance process.
Currently I have the two piece Classic Cooper S two piece damper fitted to my 1380cc engine but the whole engine has been fully balanced.
Below is a BL damper pulley which has been machined (the centre front bright part) because it had a piece knocked out of the centre. Machining the centre makes the damper pulley the same style as the later damper pulley which did not have the centre retaining flange.

- Damper pulley 1.JPG (914.82 KiB) Viewed 874 times
Because of the way the metal has been removed it would not necessarily require re-balancing. Removing the front centre flange allows for examination of the rubber joint between the inner and outer metal parts of the damper.
The three holes which held the rivets holding the timing disc have been tapped and can now be used with a harmonic damper pulley removal tool.