Questions? Looking for parts? Parts for sale? or just for a chat,
The WD Motorcycle forum
These can be helpful to those with machinery. https://pesltd.uk/?product=02-0861 Mark
email (option): pes.sales@btconnect.com
Marks washers are exactly what's required for an M20/21 head...iron or alloy...Ian
email (option): ian@wright52.plus.com
The numbers could be it, but try finding an ally head. They seemed to have been binned when replaced by iron ones. Sidecar outfits were owned by folks that generally couldn't run to a car, not keen mechanics
email (option): jeremy@clogmaker.co.uk