I'm under the impression that these are now discontinued so no longer available new, but from my admittedly minimal "investigation", it seems the 6 berth was 410cm wide, and the 8 berth 500cm wide.
As it's the width that usually seems to be the critical factor with front fitting extensions, I'd say no, it doesn't look like yours will fit the 8 berth.
Ive just been given this tent how do you find it? im not going to be able to put it up until i get to a campsite as it wont fit in my garden but im hoping it will be strong enough to hold with some of the weather we have
Its very large so finding campsites with big enough pitch will be a challenge
------------- Shels
Easy Camp Tornado 3, Vango Banshee 300 Pro, Airgo Air Genus 400