Help identify some old rocker arms

[56Lotus]

My brother has just managed to purchase a very rare Alta head conversion for his Morris 8. The alloy head is in remarkably good condition but the rocker shaft and rocker arms are very worn. He can remake the rocker shaft himself but is hoping the rockers arms are off another car and not bespoke to the conversion. He could get them sleeved but buying new would be easier.

There seems to be the code 21645A on one side and the mark SOS on the other







Any ideas or suggestions all gratefully received.

Thanks

Jon Adams

[56Lotus]

Come on guys, stop enjoying the sunshine!

[paintman]

If it's just the rocker arm bores that are worn could he not have them bored & lined?

Google says that the Alta heads were also used in the Morris Minor so perhaps the Morris Minor Owners club could help?