Fatal Push is actually becoming somewhat of a staple for black in some decks, but I've never seen more than 3 at a time. I would still count on both it and
Dismember in anything that needs it.
My first question would be is whether or not this is specifically a casual or a modern format deck. That dictates which cards would be recommendable. It would be very beneficial to look for getting the most bang for your buck in this case. For example, instead of having a vanilla
Kalonian Tusker, you could get
Garruk's Companion (3/2 for GG and has trample) or
Snapping Gnarlid (2/2 for 1G, and gets +1/+1 until EOT whenever you play a land). Also, I would recommend more ramp as well.
Llanowar Elves,
Whisperer of the Wilds (personal favorite), or if you're feeling like you want to splurge a little price-wise,
Birds of Paradise and Noble Heirarch give you access to other colors if need be. This would open you up a little more to playing
Beastmaster Ascension,
Vigor,
Stomper Cub,
Bane of Progress,
Baloth Woodcrasher,
Chancellor of the Tangle, etc. I would also mainboard 4-of Blossoming Defenses. Hexproof is kinda good, and its a pretty good combat trick.
Prowling Serpopard is great protection if you're a more creature-focused deck, but it isn't a beast.
Obstinate Baloth and
Thragtusk are great additions, and I think you have a good number for mono-green stompy.