Have you tried Priory Magnetos?
He's not just for sparky stuff.
His parts list is POA for this so he may or may not have one. Worth messaging him on here (beezermac) as his site says he's closed til September, but that might just be for taking on mag jobs.
I ordered a dozen bits from him a couple of months back, some of which I couldn't find anywhere else, saved me a fortune in postage.