Identifying Chevy engines
Identifying Chevy engines isn't that difficult if all that's needed is to know whether it's a BBC or SBC, or a six or V8, etc. But to get into the finer points requires digging deeper.
The easiest way to identify a Chevrolet engine is by the casting numbers that are molded into the block. These are generally by the transmission mounting surface on the drivers side of the block. Once you have the number enter it into Google and you should get several links to sites that have compiled this information. I am not listing them here as they tend to come and go.
Other external identifiers
While not 100%, a BBC engine can be ID'd for being a 2- or 4-bolt bottom end by looking above the filter mount: