If you're just going for the look or function then Minoura makes two products that can be used to mount a cage to a handlebar:
http://www.bikemannetwork.com/biking/p/ACH2OSYS/WC3002
http://www.bikemannetwork.com/biking/p/ACH2OSYS/WC3101
I've used both and they work well. The second one may be a tight fit for some stems but it holds the bottle a little lower. Use chrome steel cages to complete the period look.