Tiger, I just hung a chandelier like that. How deep is the canopy? Mine had a nice 2" deep canopy with a set screw. I went to ace hardware and got their smallest hook with machine threads on it. It was a 1/4-20. Then I installed it on a flat fixture strap using two nuts and two washers. It only stuck out about 1", leaving plenty of clearance for the canopy.
If you don't have a deep canopy, you could get some fender washers and fasten the hook thru the center KO on a metal 4/0 box.
