Spun rod bearing in my engine, Series III is cheaper than Series II, should I?

[Booba5185]

Just like the title says, my car just spun a bearing and I'm looking around for a JY replacement. I found a few Series II's, 120K for $750, and 154k for $700. The kicker is I found a 155k Series III for $650. I haven't had the car long (3 weeks), so I haven't had much time to look into upgrades and whatnot, but I have seen the Series III a better setup. Should I buy the Series III and swap it in? What all is involved with the swap?