Hence why I laugh when I see people talking about something being blueprinted, and especially seeing someone selling a "stock blueprinted" engine for over $400 more than it cost out of the box. It's an overused, and misunderstood word. It's kind of like the other day walking through the convenience store passing by the bottled water cooler I actually saw a bottle of water that was "100% pure organic." It's a catchy phrase, but all too often only used to sell something at a higher price but isn't actually any different than the one sitting next to it. For the record, water cannot be organic simply for the fact that it does not contain carbon...but man, it sure sounds refreshing, doesn't it?
Smaro, you should find out if the guy selling the $670 blueprinted stock motor can make sure he uses organic parts, ya know, just to ensure you get the best of everything. It might cost you an extra few hundred bucks over the blueprinted one, but hey, it'll be a really nice stock motor.
All joking aside, and to again try and stay on track, my personal suggestion is don't pay way too much for something that isn't really anything. Find out your exact rules for the class you're racing and make sure your motor falls within those rules. If you want to take it apart and make sure it's all torqued properly and has proper clearances then go for it, just make sure you don't alter it to be outside of what's allowed....well, that is unless no one ever actually tech's the motor, then I'd just find a different track to race at if you don't have the funds to keep up with the people who aren't following the unenforced rules.