This is a good build that will be very good for gaming but not for overclocking as you wanted. If you disapprove anything let me know so i can make changes.
As for your graphics card, an RX 480 ($200) should completely max out 1080p gaming but if you are planning of playing at 1440p in the future you can go for the GTX 1070. Though the RX 480 should also handle 1440p very well. If you want to spend your original budget since a RX 480 + this build should come to about $800 i can swap the processor out for an i5 6600k and increase your storage if you like.