need help figuring out what type of engion in it i was told it was a big block 400

Go here
http://www.nastyz28.com/chevy-engine-code-stampings.php
http://www.chevymania.com/
http://www.mortec.com (http://www.mortec.com/)

it will show you where to read the number off the block and then search the type and displacment of the motor.

Darrin