I wouldn't use that spoke on the rear DS, PERIOD!

For a 1st build, I wouldn't use that spoke at all unless you have a tension meter.
If you don't have a tension meter, I wouldn't use that spoke, PERIOD.

On the rear DS, your tensions are getting close to where you'll stretch the spoke beyond the elastic limit with a relatively minor overtightening misstep.

You might read this thread-
http://www.bikeforums.net/bicycle-me...on-wheels.html