hi,
i think zoo, (but all unpowered deck in general) MUST play only 2 color.
So, i think it's better thr r/g version.

Mana Base
4 Waste
1 Strip Mine
( This it's a must, mana denial in an aggro deck is perfect)
4 taiga
4 Wooded Foothills
2 windswept Healt
3 Forest
2 Mountain
1 Lotus Petal
21

Creature
4 Kird Ape
4 River Boa
3 Wild Mongrel
2 Gorilla Shaman
13

Spells
4 Rancor
4 Linghting Bolt
4 Incinerate (preferred to chain lightinig to escape from chalice set 1)
3 Null Rod

49 Cards.
there are 11 free slot. in this slot you add card for your metagame, if the mata is full of artifact deck you can put artifact mutation, naturalize, R'&'R if there are some combo you add some pyrostatic Pyllar...
if there are control deck hidden gibbons is a great choice
if there are some hulk-smash Maze of Ith is the perfect Card

Other nice Cards
elvish spirite Guide
it provide you acceleration for cast null rod or pyrostatic pyllar at 1° turn

SkullClamp.
It's a small draw engine. You can eat crature you don't need or equip a crature for a chump block to draw 2.

Bye