They will stretch out of shape over time. My preference is YLI Jean Stitch thread. You will work in the back half of the stitch and place the bugle in the first yarnover. More or less bugles per round will change the gauge. Use a medium twisted wire needle to string the bugles.
Bugles have their own strange peculiarities.
You will not be able to see the rope shape until after about 8 or 9 rounds. For your first bugle rope, do not try to carry the thread, it will be more difficult to see the stitches. Do not use black or other dark thread which makes it more difficult to see the stitches. Because you are working in a spiral, have a bugle in one stitch and a thread stitch next, it is easy to add or delete stitches instead of continuing with 10 sts in the round. . Stop and count the stitches every so often to be sure you have 10 stitches around.