Just as an aside, with Rayquaza's STAB, the power of Dragon Claw is boosted to 120, past even Earthquake. Also, if I'm interpreting you correctly, you're saying that Dragon Claw would benefit from Dragon Dance - Dragon Claw is special, so it would not. Either way, I'd personally sub it in over Ice Beam - it doesn't exactly have a good set of advantages, but the only thing resistant to it is Steel. I'd replace Ice Beam because Ice Beam's advantage over Dragon is covered by D.Claw, Grass is covered by Flamethrower, the advantage over Flying is covered by the fact that every flyer has another type and Rayquaza's other attacks can handle a lot of them, leaving only Ground... and that shouldn't be that big of a deal.
But that's just me.