Granny shoulders the load.

I measured out 30 pounds of quarters and set up the pull tester. the Spectra lines tied with a dacron sleeve and granny knot easily passed the test. The best part was getting the lengths equal. I make one line to the length I want and then tie on a thimble to one end of the second line. Then hook one thimbled end of each line to the same spot/nail and mark the length of the finished line to the unfinished line. Then sleeve and granny knot tie the last thimble to the second line. I put a knot in the tag end and run the knot up close to the granny knot for security.  I tried to get the needle into the 20# backing but it didn't go for beans. It looks like 30# is the only usable option.
  I tied a ferrule using the same method as the lines and then tied the other end of a 2 foot long piece of Spectra to my Exacto handle using the fly line backing also. Then I hooked the ferrule end to a fish scale and did a destructive test of the granny knots. The Spectra line parted about in the middle of the run at 25 pounds. I don't have  the Chatillon pull tester the factory uses which accounts for the large difference in pull test measurements. But the test did prove the value of using the dacron sleeves over the Spectra line and the granny knot. This method allows you to get two lines close to the same length every time.