The build you're looking for does not exist. Trust me, I've been searching for it ever since I started playing the game, and it's just not out there.
No matter what you do, you will never be able to meet or beat the damage output of a scythe sin. Sorry.
Oh, and you can forget about beating the scythe warrior, either, unless you've either got an ER healer constantly spamming shield guardian (or otherwise having one enchantment end on you per second) on you (in which case, you can take WS instead of zealous vow), or if you have red rock candy as your IAS (then you can do slightly more damage than a scythe warrior, but only just, and he's still got significantly more armor, especially when stripped, which is when armor really becomes relevant in HM). But outside of those two situations, there is no way you can match a scythe warrior in damage.
I have the relevant calculations, if anyone is interested. What's really sad about it is, I've done them so many times that I've memorized some of the parameters.
