I would still post your bag in the --- Authenticate This MJ --- thread. There is more to the authentication of a Blake than reading the back of a zipper head. There are fakes out there that do use riri M8 zippers.
I don't want to rain on your parade, but I agree ^^ - the zipper may not be the only thing to look at and for peace of mind, getting the girls in the MJ subforum to authenticate is a good idea. Hope it is fine.