Your timing is perfect, September and early October are best for Vancouver Island Rivers, the Stamp river would be my first choice, also Cowichan river is good for salmon and brown trout. Guides that i would recommend would be Murphy Sport Fishing, Dave and Marilyn Murphy are great people and have the island covered, fresh and saltwater, they have a lodge on the stamp river as well. For the Cowichan River area, Kenzy Cuthbert is well known and also have a lodge on the river. Spey is not necessary on the island, your better off single handed stripping flys vs spey and swinging flys. I try to get my guests to use single handed because swinging flys often result in foul hooked fish when the river is chalked full of salmon. You also might want to try some beach fishing for Coho, lots of fun with 7 or 8 weight fly rod, floating line or slow sink tip.
Good luck and feel free to e-mail me if you need more info firstname.lastname@example.org
Enjoy BC, Vic Carrao.