Yes, I can assist as I had to source one a couple of Seasons ago.
Unfortunately I failed to locate an "off the shelf" stanchion with absolutely correct dimensions so some modifications were needed.
Eventually I found the very helpful people at SL Yachting.
What you want to start from is their YS7165 stanchion.
http://www.sl-yachting.c...pered-stanchion-i67.html
If you look at the diagram in the link the measurement "F" at 315 mm is exactly correct for the location of the Guardwire holes.
However it is too long at 635 mm. SL shortened the overall length ( to 590 mm from memory )and then drilled a new locating hole 25mm from the bottom of the stanchion. Of course that could be done DIY but they only charged a small amount extra and it fitted perfectly on to the Boat. The most difficult part was getting the guardwire swages through the ferrules.
Their details are :
SL Yachting Ltd
25 Orchard Avenue, Chichester, West Sussex PO19 3BG U.K.
email: mail@sl-yachting.com
Steve: +44 (0)7798 733 608
Suzanna: +44 (0)7786 265 942
Website: www.sl-yachting.com