I am also building a Big Daddy and a few days ago ordered some 200# Kevlar from thekevlarstore.com. It arrived in the mail yesterday just in time for me to be able to put it on and install the motor mount.
I did something different with my Kevlar. I tied it to the motor tube behind the upper CR, but instead of running it through a hole in the CR at the edge of the motor tube, I ran it around the outer edge of the CR at the tube fin slot, and the fin covers it. I had some concern about the Kevlar zippering the CR, so I've reinforced the back of it where the Kevlar goes from the motor tube to the body tube with a piece of popsicle stick. I'm also going to glue the Kevlar to the body tube with a piece of card stock for a couple of inches above the CR. This should keep the Kevlar further away from the heat of the ejection that if it were right at the motor tube and hopefully protect it better, while also providing a strong shock cord attachment.
Edit: I realize none of that addresses your question. Sorry to hijack the thread, but I wanted to share what I'm doing on my Big Daddy.