Figured it out, answered my own question lol. This is what I did:
1. Assigned /boot/efi to /dev/sda2
2. Did not install Grub
3. After install: sudo update-grub and then sudo grub-install /dev/sdX from https://www.howtoforge.com/tutorial/repair-linux-boot-with-grub-rescue/
Install went fine except Nvidia issue, I have GTX970. To resolve this I did: 'e' on Grub screen entry for Sparky. Then added nouveau.modeset=0 as here: https://community.linuxmint.com/tutorial/view/842
. There are quite a few options mentioned, nouveau.modeset=0 was the one that worked for me.
Hope this helps some one else.
Cheers