good build,just made an account to tell you wat i thought
i went 8/3/5 (but i'm not very good with evelynn, i'm kinda new).
maybe you could put a playstyle section in? it'd help a bit

If anyone is wondering, with full-stacked Guinsoo's and a Nashor's tooth as your last item, you have 423, without 30% from Rabadon's Deathcap and the mana modifier from the Archangel's Staff.
With either Nashor's Tooth or Youmuu's Ghostblade, you'll easily achieve max attackspeed with ultimate on. You'll have 82%attackspeed with Nashor's Tooth and fully stacked Guinsoo's Rageblade. With the Youmuu's Ghostblade active and full-stacked Guinsoo's Rageblade, you'll have 82%attackspeed aswell.
So, for the offensive end-game item choices, you'll want to choose on if you need more autoattacking power, or spell-casting power, and also if you want to activate for speed, or have the constant attackspeed.
With Guinsoo's Rageblade and Youmuu's Ghostblade, you'll have 172attackdamage (Not completely sure, I can't remember, I'm going off the Mobafire stat info, but it may be outdated). Without Youmuu's Ghostblade you'll have 142attackdamage.

If you don't take Youmuu's, endgame your stats will be 82%attackspeed (Or 32% if you took Banshee's Veil), 142attackdamage and 423AP (Although I haven't checked this with Archangel's staff mana bonuses, and [[Rabadon's deathcap 30% modifier, but I assume it'll be anywhere from 500-700AP).

Anyway, can some people please give me some feedback? I've had 223 views and no comments.
Yours sincerely,
Adeori

EDIT :- For my working out of AP somewhere in this comment, I forgot to include runes, but they all come down to preference anyway.