If the holes are a couple of mm apart I'd guess they'd make new ones. I cant tell from here though!
Ring mounting screws are thin enough to self-tap. You dont need to drill. Just make sure you line em up straight, postition the ring accurately first, tape it down and put some elbow grease in.
Edit: but filing a mm or so for the wp to fit on either side of the ring wont do any harm. Just take your time, dont go nuts, you cant put material back on it, and try nad get some rounded files or sandpaper for the corners, because you'll find that a flat file leaves quite conspicuous cut marks in the corners. You'll wanna fix them.