Hello Ian,
If you already have a broken one my advice would be to have a new one produced from a solid steel billet rather than trying to find a cast original.
I was lucky a few years ago to buy a pair from Barry Hartnell of Swap Shop Wangaratta for a reasonable price Try the phone to him he may tell you who made them. He sometimes has reverse levers hand pumps and other bits for Dougs.
I would think a pulley place or machinist would make you one cheaper than the o'seas postage.
regards Alan.