Personally I would get the 920 as since you are overclocking they are basically going to be the exact same processor.
Here is a comparison of the cheapest Gigabyte mobos I would consider.
http://www.gigabyte.us/Products/Motherboard/Products_ComparisonSheet.aspx?ProductID=3317,3277
Basically for an extra 30 dollars you get two more RAM slots, two SATA III ports, and two USB 3.0 ports. Basically a little bit of expandability in the future. So decide if its worth it for you. Note that neither of these boards have dual x16 pci-e 2.0 slots, but it shouldn't be an issue if your not going multi-GPU.
If the total for the entire build is $600 your going to have to pull a lot of strings, but may be possible depending on how many parts you are reusing.