Dear Rob,
I have no idea regards fret-wire, but am happy to offer my services to find out for you. If you care to post your bass to PO Box 666, Chelmsford, I will personally take it around the world until I find a match. I estimate that this should take us well into the 2030s, but I am sure you will be more than pleased with the result.
Snorkie635
Just outside your back door, checking the locks work. (You never can be sure).