Upgrade SEPM 11.x to 12.1.4 + switch DB from internal to MS-SQL

Hi guys,

I need to upgrade an existing install of SEPM 11 to 12.1.4
On the same time, I need to bring the DB from internal to Microsoft SQL on a separate server.

Existing infrastructure:
- Windows 2008 x86 (Single server)
- SEPM 11.0.6100.645
- Internal DB

Target infrastructure:
- Windows 2012-R2 (Single server)
- SEPM 12.1.4
- Separate MS-SQL 2008R2 server

Of course, I need to be able to switch my clients from the old infra to the new one.
I also need to migrate settings and policies.

What scenario would you advise in order to achieve those prerequisite ?

Thanks in advance !
JTD