Hi, there are a couple of tutorials on this very forum for setting up Windows KVM with GPU passthrough in Virt Manager (VMM).
First things first. You probably need to use OVMF, since setting it up with BIOS can be tricky/require some extra stuff, where OVMF normally works out of the box on most GPUs that support UEFI.
If you are unsure if your graphics device is bound to vfio, run lspci -k in terminal to list your PCI devices and what driver they are bound to.
IOMMU grouping looks stellar, GPU has it’s own group so there is nothing there than can cause any issues.
Furthermore, check out the following link, it goes to a tutorial on setting up KVM with Virt Manager. Did the same setup a few weeks ago on Ubuntu 18.04 and can confirm it works.
https://forum.level1techs.com/t/play-games-in-windows-on-linux-pci-passthrough-quick-guide/108981