I'm fairly sure the FX-6300 would bottleneck, because it's a $100 processor paired with a $500 SLI solution. Anyways, I don't think you should SLI because that would mean replacing the motherboard (and since you replaced the motherboard you'll need to change OS if you're using the OEM version) and the psu so you can actually SLI. I think you're better off selling the GTX 760 and going for a stronger gpu like a GTX 770/780. That way, you don't need to replace the other parts as well.
Also, I would go for a FX-8320 and overclock it so you won't get a bottleneck.