Actually, the FX6350 is a "higher binned" CPU. It has a higher TDP as well.
Essentially what this means is, the silicon is rated for higher voltage. That puts the silicon on par with the FX8350.
If it's in the same category...FX8320's will OC to 4.6-4.8 GHz reliably on air cooling, and FX8350's will hit 5.0+ GHz with good air cooling.
For overclocking, the FX6350 might well hit 4.8-5.0 GHz because of the higher bin of the CPU.
I think for $20 more (as much as the FX6300 used to be) it's a very sound buy.