The FX-8350 is quite overclockable with the right MB and cooling system.
Unfortunately the ASUS M5A97 Le R2.0 does not have DIGI+ power control to adjust LLC and CPU current capability. So you are limited in that aspect.
Your board should run the FX-8350 chip at 1.375V@4.0GHz (and up to 1.425V for 4.2GHz turbo)
Do not go more than 1.5V on the core and keep an eye on your temperatures during stress testing.
It is of coarse dependent on the Cooling system and quality of the chip you have, as to how high you can take your OC. Your OC will be limited too by heat generated from the MB VRMs.
Here is a good OCing guide:
http://www.overclock.net/t/1348623/amd-bulldozer-and-piledriver-overclocking-guide-asus-motherboard
You should take into...