I would change 1 phantom dancer to a zephyr. i would put health per level seals, magic resist per level glyphs, armor per level marks and health per level on quintessences.

Too much AS. It gets you at 2.6 attacks/s, while you're limited at only 2.5. and you lost a part of the ultimate.
No way to survive if your ennemieskjnow how to focus someone or have a stun.
Or if they have an AP carry that knows how to burst someone down.
And, icing on the cake, having crit and AD is way better than getting 100% crit, do the maths using cost efficience of items.
And furthermore, you give no details at all.

Well, what I would do is Replace a Phantom Dancer with a Guardian Angel but overall Ill try this guide when I have the time.