I have actually discovered that my USB to PS/2 mouse adapter does not work, and it's not really worth finding another one (for me at least), so a single PS/2 slot is fine for me. Sorry I wasted your time!
I'll be getting a Gigabyte GA970A-UD3P. It's a very good motherboard for overclocking on a budget. It also had good slot positioning, as I can put a slot fan above the GPU to cool my VRMs.
Again, extremely sorry I wasted your time. Thanks anyways!