Check this out :

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=2487749950&category=6164

Interesting, you thoughts guys ?

I think what he's saying is... its an SS396 (verified by the 138 in the VIN of course) Then without coming out and saying it, he's saying that the #'s 396 is gone, and was replaced by a rebuilt 427 that happens to be a rare block of somesort(probably ie out of a supercar or vette or something rather than an impala or something)
Thats my guess... basically a 396 car with a NOM which is a 427 thats nicely built.

I believe the L-72 was rated at 425.
I see it as he states (and Russ) a 68 SS396 with a 427. Here is his ad on TC:

68 SS396 with 427 (http://www.chevelles.com/cgi-bin/classifieds/classifieds.cgi?db=1968&website=&language=&session_key=&search_and_display_db_button=on&results_format=long&db_id=964&query=retrieval)

Need help identifying if this is a COPO Chevelle. It's a 68 Chevelle SS396 but the engine casting # is 3963512. other codes include: 195L50369 Hi Perf KFA68 and/or KF 68. This is the engine that came in my SS. I'm not sure if it was replaced or not, I've had it for 9 years. I did have it rebuilt 100%. However when I obtained it already had the 427. Should I get my hopes up??

Maybe I'm taking a huge risk by selling this chevelle and not even realizing that it could be a COPO, how can I verify that? Casting #3963512

Marco,

The 512 Block did not come out until 1969. Other than dealer transplants all info avalable indicates Chevelles did not get 427s at the factory in 1968.