[HG] Chanterelle string for low D

[hurdygurdy]

Hi all
I'm not usually one to plead for help but this problem is costing a lot of 
time and money so any help will be greatly appreciated.

I've just built a three chantrelle gurdy 345mm scale length and am tuning it 
to normal D/G tuning . The third chanterelle is to be the next octave D 
down.

Has anyone found a string to achieve a reasonable result at this pitch ? 
I've tried a lot of viola C strings with limited success.

Regards

Neil Brook