In the beginning of the game you should be focused on being a stun gun and farming as much as possible. You max enrage early so that you gain the 3 bonus hp per minion kill early. By mid to end game you should have a lot of health. I usually end up with 2.8k health around end game before buying a warmog's or any health items. You should be fine if you farm correctly.

I like AD Sions. I really do but this build is screaming "Kill me plx"

Yes you WILL do insane damage if you manage to survive the CC and focus on you and YES you WILL heal youself at insane rates with your ultimate on. what this build needs to improve is some more survivability especially earlier on in the build.

Maybe before building the Yoomuu's Ghostblade so you can benefit more from the Avarice Blade's Money.

boots so late?

I like this idea. :D

Your guide is also pretty well done, but it could use some work as far as tips/techniques and the description of game phases. Try to be a little more specific I guess. Annd if I were you I would put "Stun" as one of his pros, because it is so awesome.

Overall, I like your build and guide +1