Good Short Block?

All right guys my plans have changed a little. As some of you may know through my other posts, I have a 66 Lemans that has a 396 in it. Well the 396 is was sick, and I was hoping to rebuild a 454 before the 396 fell out, mostly to learn more about hot rodding. Well i didnt make it. So I am now planning on getting an already built short block, and taking my time to build the 396 againg whick will allow me to pick up some more knowledge. Anywho to my question. I have found what may be a good short block on-line, however I need to know what questions to ask in order to not get screwed, after all the 396 that was in my car was supposedly 'freshly built by a pro,' and I saw how that went. Here is the describtion the guy has in the ad:

454 BIG BLOCK CHEVY.
BALANCED AND BORED .060 OVER. FITTED WITH KEITH BLACK HYPEREUTECTIC PISTONS. SHORT BLOCK IS FULLY ASSEMBLED. HAS NEW BRASS FREEZE PLUGS AND CAM BEARINGS. HAS 108CC OVAL PORT HEADS. HEADS HAVE BEEN CHECKED BUT NO MACHINE WORK DONE. WILL HAVE 9.9:1 COMPRESSION RATIO WITH THESE HEADS. MOTOR HAS NEVER BEEN FIRED.

COMES WITH MISC. PARTS INCLUDING BALANCER, FLYWHEEL, CAM, INTAKE, LIGHTWEIGHT MANUAL STEERING BOX, AND MORE.

BLOCK CASTING NUMBER IS 361959 AND HEAD CASTING NUMBER IS 353049

Please tell me what I should ask to find out if this is a good short block. Also can I make my desired 500 hp with this set up, and some cast oval port, stock heads. Thanks for all the help.

This is about the best bargain in terms of a big block. It isn't quite a short block, but it has an all forged bottom end and a low compression ratio that is just asking for a supercharger, but makes plenty of hp as is. http://store.summitracing.com/partde...2&autoview=sku It's GM's 454 H.O. GM has a 502 long block for a little less, but this one is almost complete.