That is a serial number, not a casting number. There is a great resource for looking up this kind of information at nastyz28.com, but that suffix isn't listed.
I have an early (88ish) 345 hp crate motor that ends in zzz, so I'm assuming your engine is a 345 hp crate motor built in Flint, Michigan on August 1 in the mid-nineties.
What engine casting number is 14010207
what does the casting number GM 3892657 say about this engine block
What Chevy engine block has the castin I mean casting number 397004
3963512 is not a part number. That is the block casting number for Big-Block 427 or 454 engines
350 cu/in block used in GM Goodwrench Crate Motor. Made in Mexico.
Sometimes the website linked below can be helpful.
Find the casting number on them... type "GM (insert casting number)" into a search engine and you should find what you're looking for.
1966 or 1968 327.
350
That block was used from 69-80 to build 302's, 327's and 350's.
It's a 4" bore block. Has been used for 302, 327, and 350 engines.
Check out this site, http://www.nastyz28.com/sbchevy/sblock.php