Classic/Antique Car Repair: chevy truck

Question
have a 1966 chevy long bed truck need to fine out if it has a 283 350 or 327 eng best way to find out thank for your time.

Answer
There should be a series of numbers and letters stamped on a pad on the right front corner of the engine block right below the cylinder head. The pad should be visible from the front of the engine on the passengers side. If you copy those numbers and letters and send them to me I will look them up in my reference material.
Brad