For the 12.1.671 you need to contact with Technical Team.
Better is that you can upgrade in SEP 12.1 RU2 MP1 and then install the new Server in same version 12.1 RU2 MP1.
It available in File connect
https://fileconnect.symantec.com/
https://www-secure.symantec.com/connect/articles/latest-symantec-endpoint-protection-releases-symantec-endpoint-protection-121-ru2
https://www-secure.symantec.com/connect/blogs/latest-symantec-endpoint-protection-released-sep-121-ru2-mp1
For replication folow it
https://www-secure.symantec.com/connect/forums/replication-between-sites-sepm-121-ru2-mp1-and-sep-121-ru1-mp1ru2