What should I pair my R7 370 2gb with?

[sandigamer]

So, I've been thinking about pairing my GPU with another one.
I have a Radeon R7 370 Asus DirectCU II OC Strix Gaming 2GB Edition GPU.
Would it be good to pair it with the 4gb edition and if not, what should I pair it with?
Would I also need to upgrade my CPU (AMD Athlon X4 860k) to not bottleneck my GPUs?
I'm on a $200 budget, but I would save up some more for better parts if necessary.
Used GPUs and CPUs don't cost much here in Croatia, So I should definitely be able to find something.

 

[Vic 40]

If you have that kind of money get one better gpu and sell the one you have.