I presume it is pre-1980 in which case make sure the oil is GL-1 (ie non-EP), some places are selling SAE140 GL4/5 which is wrong and may not be SAE140 at all but just a badged multi-grade (85W140 or similar). But you probably know all that.
No idea if any of the local chandlers will sell it (I suspect not) but if you phone them they may be able to suggest somewhere.
My oil specialist (Opie Oils) only sells it in 5 litres and is out of stock.
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