I have no experience with the Gen 1 system. I do know from my understanding is that System 7 and NS2 are 2nd Gen. The names are different from North America and Asia. Example in Asia its KSC and over here in North America its KWA.
I don't know whether the slides of the Gen 1 and Gen 2 are interchangeable... maybe the OP should look into it a bit more. Would suck spending over 60$ for a slide and barrel that you can't use.