Well, Congrats! You in fact have the Version 2 motherboard, and all of the processors that have been listed for the Z620 over the years should work fine for you (both the ones for the Version 1 and the Version 2).
Processor upgrades probably right now are the lowest priority..... fun for the future. Even your old boot SSD will be a huge improvement over the HDD it came with.
I'm very happy you have this version of the motherboard..... you don't have to worry about that any more.