About 10,1 smbios... probably it works too and both without issues...if you want I can make a test.
About FaceTime issue...prior to install Mac OS sierra (from El Capitan) and make changes to the smbios definition I have made a backup of the old parameters (just for safety)... then with clover configurator I have changed ONLY the smbios part with the automatic wizard tool included.
I have then replaced only the new serial with my "old" one. Also make sure that the MLB isn't changed after all... (must be your previous one).
By doing this now on system profiler macOS detects that I have a macpro 3,1 (because it follow the serial number) and on Apple Store it detects an iMac 14,2 and it allows you to download Mac OS sierra and proceed to the installation.
For now all is working perfect.