This is a Canadian produced car and those records include the engine code.
Where his engine code should be, it's basically blank - K00000//. Not sure how common this error is in the data, but I'd guess it was either a computer issue or a data entry issue. Either way, it's not there.
On the GM of Canada sheet, there's no RPO code for the engine. That's because the 396 is included in the SS396 package and is not a RPO. If they had ordered the L78, it would have appeared as an RPO.
What's really neat for us is the page shows a list of VINs (far left column) and the engine dates - data that we never see.
One major note is the engine plant source is mostly McKinnon and they only supplied a few Canadian plants vs the dozen+ US plants. Engine batch size (and thus dating) will be very different than Tonawanda or Flint.
Still, note that most engines have the similar dates, until they hit some older March DE blocks. And there's a typo - the 0428 engine date should probably be 0328.