So after some help from Alexey, I have decided to upload my 4.13 preview 1 branch. Currently only a partial VXGI integration. Shadow mapped lights currently do not work with VXGI, everything else should be the same as 4.12.5. Use this branch at your own risk, I will not be providing any support for it until 4.13 is finalized.
Link: https://github.com//UnrealEngine/tree/4.13_Preview_NVIDIA_Techs