I'm all for heavy arrows for big game hunting in general. Easier on the the bow, better energy transfer, and the bow is a little quieter with them. I think heavier arrows tune better as well.
My current setup is a 495 grain carbon arrow flying at 290 ft/s (125 gr broadhead 70lb. 30.5 draw) Shot quite a few bulls with it. That said I also killed some, with lighter arrows in the past.
Like the above posters mentioned those will all do the trick, it's more of a matter of preference, but I wouldn't feel very comfortable at all below 60 lb (let alone when using a mechanical broadhead) They don't all stand broadside, and have thick ribs.
I don't mind being "overbowed" (if there's such a thing) for moose, elk, or whitetail bucks for that matter.