AP item changes should have addressed Viktor's Hex Core

Viktor has had very high damage for a long time, but the recent AP item changes have exacerbated the problem. This is because the AP granted by Luden's/Zhonya's was dropped to 100, with the ratio on Deathcap increased to 35% to compensate. Viktor's Perfect Hex Core was already the single largest source of AP in the game (+168 for a level-18 Viktor) outside of 19-stack Mejai's, and with the bonus from Deathcap it grants a whopping 226.8 AP (241.8 if you build Seraph's Embrace, since Perfect Hex Core also gives 500 mana). It's also not overwhelmingly expensive at 3000 gold for all upgrades (vs. 3500 for Deathcap). Here are some example full-AP builds (5 items, not considering runes/masteries) to provide an example of how Viktor stacks up against other champions:

1. A typical Viktor build with Perfect Hex Core, Deathcap, Void Staff, Zhonya's and Luden's gives 767 AP.
2. A comparable non-Viktor build with Deathcap, Void Staff, Zhonya's, Luden's, and Rylai's gives 675 AP.
3. A max-AP Viktor build with Perfect Hex Core, Deathcap, Seraph's Embrace, Rod of Ages, and Zhonya's gives 860 AP.
4. A comparable non-Viktor build with Deathcap, Seraph's Embrace, Rod of Ages, Zhonya's, and Luden's gives 748 AP.

Now, there are certainly some counter-arguments to the idea that Viktor needs nerfed:

1. Hypothetically, his AP ratios have been balanced around Perfect Hex Core as a high-AP item.
2. Perfect Hex Core takes a while to scale up.
3. Viktor has other weaknesses, most notably his low mobility.

I'm still inclined to think that Viktor's damage was already on the high side before (just try using Death Ray on a creep wave), and that the AP item changes have made his advantage even more pronounced. Personally, I think some stats need to be shaved from Hex Core to make it a little less overwhelming. Maybe something like -10 AP from all upgrades and/or -1 AP/level overall? (I'm no balance expert, but I think that minimally, it should be dropped by ~10 AP to balance the increased bonus from Deathcap.)