To the best of my "limited" knowledge, i did not think that B-50 stretched any.
As usual, I am probably wrong.
If you will contact any reputable Trad supplier, such as 3Rivers or others, and tell them what you have, they will supply the correct string. If it is AMO 64", which a 66 Kodiak should be, they will know exactly what to send you. Another good source is Rainman on this forum. He ain't so great, but his strings are.
Again, Endless loop or Flemish is your choice.