You could try contacting Chris Howard at Cyclo-Retro in Melbourne. If anyone knows he should. Also give a try to eBay.it. Since you are looking for something so extremely old fashioned an old bike might do the trick.
IMO Italian Tipo R rod brakes are the only rod brakes of the past 70 years that will stop a bike. Still not as good or as predictable as newer brakes, not suicidal in traffic.