Weapon speed for SOC is now largely irrelevant as far as white and seal damage is concerned.
Note that judgement of command is dependant on the damage range of your weapon, so even while levelling, 'bigger damage per hit' does matter, so that typically means slower is better.
Once you get CS, weapon speed matters even more (and still more once you get DS). At that point, you want CS to hit as hard as possible each time you hit it, thus slow is prefered once you get CS.
The levelling game has changed a lot since vanilla... You pretty much blitz through the levels well before you can properly finish questing in a zone and typically have to skip a lot of content along the way because you outgrow it. The same is true for your gear. Anything you get is typically going to be obsolete a few hours after equipping it for the first time. Just go with anything that drops that's an upgrade. Trying to min/max your gear while levelling is somewhat futile as you replace stuff so fast.
Khoo's is decent for a 2hander. Although in the same level range Pendulum of doom or Thornstone Sledgehammer would be much better (for BOE's). But khoo's is probably a lot cheaper and it'll do it's job. It's not like there's much 'hard' stuff to kill at that level
Tip: if you can't get the heirloom weapon... Go AV as soon as you hit 51 and hope for a win. Ice barbed spear is easy to get and will last you quite a while as 'best' until you can upgrade it with 58+ greens from outland.