ZL-1 stamping numbers

[GMH454]

Please don't get excited. This engine was a crate engine. I have found some numbers stamped into various parts of it and would like to confirm their appropriateness. Do I throw up the questions here or should I address them somewhere else for confidentiallity sake (if so where).
Does anyone actually know how many of these were made. I've heard 154 but also heard that they were cast in batches of 300.