Attached below is the part number tag:

5788673 (part number or block casting number - I'll guess that it is the part number).
261 FITTED PASS

Indicating (to me) that it is a Canadian 261 passenger/Pontiac engine, which would use hydraulic lifters.

See if you can find any of the codes shown on this page - USA 261 code locations.
Attachments
canadian passenger 261.jpg (18.81 KB, 215 downloads)