Advice on component upgrades

Right now, I'm running a Core i5 6600 non-K paired with an MSI H170A Gaming Pro motherboard. Someone just offered me an AMD FX 8320 and an ASUS Sabertooth 990R 2.0 combo, plus an R9 280 X graphics card left over from the deal.

Is this actually worth taking? I already have an R9 280 X sitting in my rig, so if I do this, which card could I realistically toss in there for a crossfire setup?😵

It probably isn't worth the swap, especially since dealing with FC Barcelona tends to cause more headaches than anything else.