Can you please elaborate on your GPU passthrough setup? I was under the impression that NVIDIA have explicit checks to see if you're trying to virtualize a consumer brand GPU and throw an error in that case.
I have a PC with a GTX 970 that I wanted to try a similar install on, unfortunately the i5-3570K in there doesn't support VT-d from what I can tell.
Those checks are at the driver level, and only for Windows (you can circumvent them by not exposing VM cpuid details to the guest).
On macOS I haven't done anything special. Kepler cards work out of box, and other cards just need NVIDIA's own web drivers installed. Even on real Mac Pro hardware, those drivers are notoriously bad. They're tied to explicit macOS updates, so most people use something like this to patch older versions if new releases have issues: https://github.com/Benjamin-Dobell/nvidia-update
From my experience with a GTX 950 and a GTX 1060, the macOS Web Driver from NVIDIA doesn't seem to care about virtualization, and it works fine (assuming the drivers and passthrough are configured correctly).
Windows is a different story, and I had to use a patched vBIOS[1] to get my 1060 working without Windows 10 throwing the dreaded "Code 43" error (when it detects virtualization and refuses to work). In my case, the CPUID workaround mentioned in another comment didn't help.
As for VT-d, I believe the unlocked "K" processors from Intel all have VT-d disabled for some reason.
I have a PC with a GTX 970 that I wanted to try a similar install on, unfortunately the i5-3570K in there doesn't support VT-d from what I can tell.