I bought my crate LS2 from Salle Chevy for around $5,000. Custom bump stick from comp cams, AFR heads Mongoose heads reworked, Jesel rockers / lifters and some custom pushrods.
The engine is right at 620 hp (crank) and should last a long time.
There's also a big list of aftermarket stuff like intake, TB, Injectors, ect. that also went into the build.
Watson Racing and Engineering in N. Calif. disassembled the motor then put it back together. Here's a link in case you want to talk to them.
LINK
Ask for Mike Blackstone. Tell him I sent you.
Good luck,
Rich