The following is what I did.
This should go without saying, but I cannot be responsible if anything goes wrong for you in this process. If you do not understand what is happening here, do not attempt any part of this process!
Inspiration for this process was taken from information gathered at these URLs
I use the unfortunaltely generically named "File Manager" by rhmsoft for all my on-device file system operations
1) Obtain Root Access to /system
If you have not already, in "File Manager", make sure to enable the "Root Explorer" and "Mount System Folders" options in the system settings. If you're prompted to allow SU/superuser/root access, be sure to allow that too. If you are using another file explorer, you'll need one that offers root r/w access to the system partition.
2) Move the APK
in the "/data/app" folder, you will find the Google+ apk file. Mine was named "com.google.android.apps.plus-1.apk" Yours may have a different dash number at the end. Move this file into the "/system/app/" folder.
3) Move the app's lib files
in the "/data/app-lib/" folder, you will find a folder with the same name as the APK in step 2. Mine was named "/data/app-lib/com.google.android.apps.plus-1/" Move the contents (not the folder itself : mine contained 13 files) into "/system/lib/" and then delete the remaining empty folder (com.google.android.apps.plus-1) left in "/data/app-lib/".
4) Reboot and enjoy!