the rings will never touch it. it doesn't stick up further than the honed cylinder, and there's plenty of bridge left there for the ring to ride on.
i would chamfer those windows, though.
i usually get in there with a long dremel bit and scare the shit out of myself a few times. it's nerve wracking and frighting sticking rotary tools into the cylinder, but sometimes it's gotta be done. right now i'm borrowing tony's 90deg rotary tool and it's making life so much better, but they are expensive if you don't have a friend you can borrow one from.