I have the same computer but with a Quadro NVS 140m. I followed your guide and I was able to install MacOS but I am not able to get it to boot. When I use the USB drive to boot the harddrive, it seems to lock up at [PCI Configuration Begin]
Should I reinstall and try again? Not sure why it doesn't want to boot from the harddrive without using the USB drive.
EDITED
I reinstalled and was able to boot now!