I didn't know Stuart made guides suitable for 8Kg as I've only seen the big jobbies like the ones on my 80lb rod. So, sorry I can't help, but I'm looking forward to hearing from those who might be able to.
For 8kg the light weight Aftco Rollers are great, especially due to their size and weight on a 8kg rod blank. I don't know anythiong better for this application of line.