Some major problems can exist here.
Namely that anything that can recycle their graveyard into their library is going to do bad things for your.
Secondly, cards like Serra Avatar or Worldspine Wurm or Emrakul, the Aeons Torn or the other Eldrazi bosses. Basically mean you can't win.
For your strategy to work you probably need something to exile their graveyard at some point. You'll probably need things that can hit at least one card at instant speed, and something else that just exiles the whole damn thing.
Scavenging Ooze is potentially a great option, he can take one of those big boys when it hits the graveyard while it's "put into the graveyard" triggered ability is on the stack. He also gets bigger and gains you one life. Having at least one creature that can attack (besides Clone if you Clone one of their creatures) gives you an out in case you can't kill their graveyard and they have an efficient means of recycling it.
You only have 4 copies of a creature that can block fliers and will only absorb 2 damage from a trampling flier. They can also die to something as mundane as a Shock spell. Short version - Fliers will kill you.
Bojuka Bog is a really efficient way to exile someone's entire graveyard, but there are tons of other ways as well.
Your stuff takes forever to setup and is ultra-vulnerable to removal and board wipes. Modern is full of decks that typically can do very powerful things very quickly.
Literally T1 wins on the draw are possible, unlikely, but possible.
Memnite, Simian Spirit Guide, Infernal Plunge, Griselbrand, Faithless Looting, Mountain, Goryo's Vengeance as a opening hand with 4 copies of Fury of the Horde in the deck along with a bunch of other red spells and here's what can happen.
T1: Draw a Chromatic Sphere, play Mountain, play Memnite, cast Infernal Plunge get RRR in mana pool, use R to cast Chromatic Sphere, exile Simian Spirit Guide from your hand and get another R in your pool, use R to activate Chromatic Sphere and sacrifice it add a B to your mana pool and draw a card, mana pool now has BRR in it. Use an R to cast Faithless Looting draw 2 cards then discard Griselbrand and just about any other card except Goryo's Vengeance or Fury of the Horde if you drew it with the sphere or Faithless Looting.
Use the BR still in the pool to cast Goryo's Vengeance and put Griselbrand into play with haste. Pay 7 life, draw 7 cards, hope you get two red spells and a Fury of the Horde shouldn't be too hard, but if you miss Pay 7 more life and draw 7 more cards, if you miss again, attack with Griselbrand, gain back 7 life, Pay 7 life draw 7 cards, you probably hit it at this point. Discard 2 red cards to cast Fury of the Horde, untap Griselbrand and attack again. If you need to, Pay 7 life and draw 7 more cards to hopefully hit another Fury of the Horde, if you do and have 2 other red cards, you've won on T1.
It's a pretty ridiculous example but that was just turn 1. It gets more and more possible each passing turn as he could play more land and draw more cards. Hell you might make it easier by milling Griselbrand into the graveyard for him.
I love Mill Decks as a fun way to win, but I think your strategy may be way too slow, counting on a huge board state that just as you're about to start doing your thing most other decks are deciding on which option they will use to destroy your entire plan, or worse calculating whether they can finish you that turn or the next.
There are cheaper decks like RUG or Jund infect decks that can pretty consistently draw T4 or better wins and your only interaction might be blockers or your 2 putrefy. Either of which will slow you down even more if the blocker dies or you decide you need to constantly keep 3 mana open to putrefy any threats.
My suggestion is to add some additional win-cons via damage and some additional removal to be able to interact with opponent's threats more reliably.
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