Actually, I would reinforce the top of the bucket, and do this centre hook plan unless you don't need to lift very high. By the time you have two side chains hanging at a "nice" angle, you don't want much more length to your load or you run out of lift, unless you can attach the side chains directly to the load with the weight evenly distributed.
Usually though, I put on the forks and attach the chain to them - they were designed for this sort of lifting, while the bucket was not. As well, with chain hooks on a bucket, you might be tempted to do things that the bucket/FEL was never designed for, like pulling backwards from a single point, or other things I haven't thought of.
Really, if you have a centre hook, or two side hooks, so long as you work well below the limits of the bucket and fittings, you shouldn't have a problem - it is always the "just a little bit more" that stuffs me up!