Server sizing for SEPM12's SQL Server

I have found sizing recommendations for SEPM 12 (http://www.symantec.com/docs/TECH163806), but have not found any documentation for sizing the SQL server if you elect to put SQL Server on a separate VM.  Can anyone point me to such documentation, or offer a recommendation for sizing a SQL Server vm for an enterprise with 6,000-8,000 machines with SEP?

Thanks - Paul