- I think it sounds like a sensible idea Taffy.
I had problems getting a replacement 'Bowden' cable for the door pull when the old one snapped a few months back.The cable itself is simple enough but the end fittings are different at each end and is an ( hard to replicate ) ,'L' shape at one of them.The universal solderless nipples are therefore no use if you attempt to make up your own replacement (I did !!).
None of the usual spares suppliers had them in stock;one was thinking of commissioning a batch of new ones....
Have you any idea whether the Rover 400 door cables were also used?
It proves , I think, that you are correct in your concern that some generic spares are slowly disappearing .....