Not sure where you are in the world, or what you have available to you for jewelry or watch repair shops....
but I would just go to a local jewelry shop or watch repair "stall" (where I am). If the place is accustomed to replacing straps & bracelets, they usually have an assortment of springbars & other replacement parts. Usually it's just a matter of the tech rummaging around in the parts bins to find one of the correct length & popping it in for you.
You may be able to find a watch battery stall in a local mall. Sometimes they will have more than just batteries for quartz watches, you may be able to find the correct springbar at just such a stall which was not even intended for vintage mechanical watches
Shouldn't be a problem ... as long as you have those kinds of shops around your area.