I currently don't know if the installer could be forced to install grub to an destined disk/ssd when two are in the box: so I would place the new ssd in the right place *before* installation.
I also don't know if "over-provisioning" is (still) necessary. is that on your radar ?
hint: I'm used to tag the edited files under /etc with # <my-name> to find them all quickly with fgrep -R <my-name> /etc/*