As I look at your pic again, I realize my post might be a little confusing. You've got your 8 holes layed out, but they are not equally spaced. My point is its possible to lay them out, all equally spaced, and not be on top of any existing hole. I've done it!
One tip I might add is google "divided circle template". It helped me understand how to go about laying out the holes.
UDS, mini wsm, 22.5" weber kettle