Metalastik bush - where from?

[Weslake-Monza]

I have some non-standard suspension parts that are fitted with metalstik bushes that I want to replace with new metalastik bushes (not polyurethane). They are probably an off the shelf bush from some some BMC/Austin-Rover/Ford/whatever car of the early 1980s. The bush OD is approx 30mm the bolt hole is sleeved and with the sleeve takes a half inch bolt. The width of the bush is 35mm. I've had no succes from web searches and the original manufacture of the part no longer makes them. Any suggestions?