My Skywatcher 200mm Newtonian atop the Celestron CG5 mount with the William optics Z66 and guide scope rings.

The mount takes this with no problems at all as long as you balance the set-up correctly, you will know by the sound of the motors when you slew the scope if the balance is not quite right.
Problem is that you need to be out of the wind with this or it just becomes a big sail!!. excellent scope for moon, planets and deep space.