They don't list strings for a scale that long but they do sell'm by the inch -
http://www.bassuke.com/Pahoehoe.html
You may have to buy several sizes to test which ones work best or maybe they already know and can offer suggestions.
I'd like to know myself if their strings would work on an upright 'stick' bass (38-40 inch scale) I'd like to make. I was planning to contact them this winter to ask about that and was doing some research when I found this thread.