The build you can see above is what i use to speedclear T13 and greater 65-70s, try to get as much CHC CHD as possible and AS second to that. if you get a skullgrasp with a very high roll in general, you should use this on your character instead of in the cube! But it's rare so you should probably cube it.
And for speeding you always use Chilaniks Chain just for the movement speed.
If you are planning on pushing a bit with this build you should switch out the Gogok of Swiftness gem for a Bane of the Stricken otherwise you will struggle alot with killing the elites and riftbosses. Here you also switch out the belt for the Pride of Cassius for the increased duration of Ignore pain.
For speeding, use red gems in everything and a purple one in your headpiece, For anything above 70 use All resist = Blue gems in all pieces but still use a purple one in your headpiece.
Always try to keep Ignore pain up, which is easy enough with the Obsidian ring,Keep Warcry and Battle Rage up at all times, and use Threatening Shout on stuff you wanna kill fast.
As usually with the hellfire amulet you would want something that you are supposed to have as a passive. a good second trait to pick if you get a good one would be "Rampage" wich gives you ALOT of extra damage!
Last i'd like to say that if you are having a trouble with resources you should use Wind Shear as the whirlwind rune for speedruns, BUT If you are doing anything from 70 and above if you are below 1000 paragon, i would use the Blood Funnel rune to restore health while spinning. You would be basicly invincible
if you got any questions feel free to ask em.