Nice.... it has the riser and second processor already, so that is a significant benefit right there. You could stage processor upgrades by taking out the second and the riser and getting your ideal one for the first socket, and buy a second later.
The Boot Block Date you'd like to see is 3/6/13 for the Version 2 Z620; the Version 1 has date of 12/28/11. You'll want to know what exactly you have as your processor, and then you can see what your heatsinks/fans are rated for. There is the usual "Mainstream" version and also a higher cooling capacity "Performance " one.
It will be interesting to know what processors you have in there right now, to know if there is room for significant improvement and at what cost.
FYI.... those adapters shown shift the connector end of the unit leftward so the physical layout perfectly matches that of a 3.5" hard drive once the two are put together. That way when you put the combination in the Z620's slider drawer and slide it in the rear end meshes perfectly with the BlindMate receiver you'll see if you peer in there with a flashlight. You can't use any converter for this purpose (but there are a good number out there that will work just fine).