I really don't understand some things about your build.

1. Why do you have that rune build? You trade so little early dmg for so much late game stats, I really don't understand it. Quints: I will leave those to you, but I would go for flat CD reduction or flat armor. Marks: Hybrid penetration, Seals: Scaling HP, Glyphs: CDR flat or scaling MR.
2. Why those masteries? +2HP5 will give you at best 72HP/min (with 2 mentioned items), 5% bonus armor will give you 5% more effective HP from bonus armor (at 4000HP and 100 bonus resistances, you get 200 effective HP before penetration takes place) There are others, that might not be worth spending points, but try to look for them yourself :)
3. Rightenous Glory - good item, but not on Zac, why not take something different one that doesn't waste stats, Thornmail is viable against heavy autoattack fed team, Locket against AP. You don't want recklessly stack only HP, but armor and MR as well. (at 4000HP, 100 bonus armor means 4000HP in effective health against phys. dmg). Another example might be 27 MR scaling runes will give you up to 27% effective HP against magic damage. (enemy's magic penetration not counted)

You should always write on paper, what are the pros and cons of certain item, mastery, rune. Then you can make a guess when it will be optimal...

(I'm not pro at playing this game, started quite recently. But I enjoy good theory-crafting XD, and then to put it in use... Well, I often don't have enough time for that XD.)