Need help with motor number

I bought a motor and trans, the guy said it was a 350 chevy. I found out it is a 400 small block. The number stamped on the flat plate behind the alternator is SAXG 6983 which doesn't match any numbers I have found to tell me what the motor is . I am trying to set the timing on it and need to know where it needs to be.

 

anywhere around 4 -8 degrees BTDC should be a good starting point.

 

There are a lot of factors to take in to consideration when setting the timing.